There are tabs across the top of your home page then there's the guid. Press your home button twice to go to your guide and arrow up and down to switch between the tabs. Move left when you're at the tab you want. When you sign in, you'll automatically go home. The store doesn't have much except for KI and MKX, nothing much accessible other than those. For fighting games, you need live to play online multiplayer. You also need live to talk in parties. A kinect is helpful for voice commands such as turning narrator on and off. My system came with one so I've had that since the beginning.

Answer to question 1:
ok, so your home screan looks like this. As mentioned by ghost rider, there are tabs right across the top such as home, , community, one guide, games, music and so on. You can use the left and right bumpers to flick between these tabs. Below this, you have a large tile which will display the currently running app or game. This tile will animate and produce sound also and you can always get back to it while your on the home tab by hitting the left trigger. Directly to the right of this, you have a column of sponcered stuff that's always changing. You can usually find links to game promotions, stuff that's gone free to play for the weekend and games with gold. To access this area, go right from that live tile and you can go up and down to read what's there. Narater calls this area the primary featured content section. Below the Your currently running app tile, you have a vertical list of stuff that you've launched recently it contains the last 4 or so games and apps that you've accessed. To the right of this, is another vertical list of sponcered stuff that can be accessed the same way that you did with the other sponcered stuff. It's more of the same, though narater calls it the secondary featured content section and it usually links you to tutorial videos of things you can do with your xbox. Below this, you'll find a section where you can pin the stuff you use most. It's pre populated with links to the store, your games and apps, OneDrive, Skype, and various other things. You can add a whole bunch of links here be it a game your currently playing to a websight. Yeah Narater will do edge... with a keyboard. You can get to your pins, or as narater calls it... My stuff section by pulling the right trigger from the home tab.
More about my games and apps:
So I mentioned it earlyer on, my games and apps is where everything you own gamewise is going to turn up. By default, your dumpped into a list of games. If they are installed on your xbox, narater will just read the game name. If it's something you've purchased digitally, Narater will read the game name, preceded with the phrase ready to install. Just press A on the ready to install icon, then move over to install and hit A again. After a while, you'll heare a notification sound letting you know the games installed. You can get your notifications in the guide. The guide can be invoked by doubletapping the xbox button, or if your sitting on the home screen by going directly left from the currently running live tile.  Going up and down will switch tabs in the guide and everything to do with those tabs loads to the left. So if you were to go down to notifications after installing a game, hitting left to get into your notification list you'll notice you can dismiss all notifications with the button at the top and use the dPad to read your notifications if you have more than one. Hitting A on a notification will let you act on that notification; For example if you'd just installed a game, then hit A on that notification you got, the game will launch.

Answer to question 2:
God this post is long. Anyway, have you done all the updates? Narater is a bunch more stable for me now. Increasing the speech rate helps a ton also if you've not done that yet

Answer to question 3:
Time for an intro to the menu button. It's that small round button right and slightly down from the xbox button. You can press this just about anywhere to get a context menue. It's like the right click in windows. This button is the key to uninstalling games, quitting apps, pinning your things to that area at the bottom of the home screen and more. So if we were going to uninstall a game for example, Find my games and apps, press A to get in there, Find the thing you want to uninstall then hit that menue button. You'll find the uninstall option usually right down the bottom of that menu that comes up. Another option you might have noticed in there is manage game. You can do a couple of extra things in here such as installing any DLC that came with your game, Backup your saves, or removing your saves if you broke something and want to start from scratch. If you want to use an external drive down the road, you can copy across your save and game data from in here too.

Answer to question 4:
Still here? My hats off to you! So the kinnect... I wouldn't bother honestly. Microsoft have gave up on it and all the voice command related stuff is going to be rolled into cortana shortly. It does make for a beastly skype webcam though.

Ghost rider answered question 5 for you with everything I'd have said. I'll only add that you get access to a few free games every month to keep with your gold membership and you also get some cloud storage for game saves. Something that I use quite a lot my self as I travel to my cousins frequently.

This concludes everything you wanted to know about your xBox one... but were too afraid to ask.

I have an xbox as well, and if you ae on home screen you use right trigger to get to my games and apps easily, as exodus has said already.

I'll try writing some things in summary form.
From home:
Going all the way up to the top is where your tabs are.
If you highlight the home tab where it says home, one of seven or whatever it says, Pressing left from here opens guide.
Going down from the top on home tab, puts you on the most recent game or app you played, if you are signed in. Press a to launch the app or game.
Press right trigger from a tile, to jump the cursor to my games and apps, if you want to manage games or check on downloads etc. Press a to launch my games and apps.
Press right bumper from a tile to jump to the next tab, and left bumper to jump to previous. Alternatively if you reach the edge of a screen it will scroll, or if you go to the tabs you can just pick a tab and press down arrow.

My post is now going into longform mode, and I do mean long. I will switch to summary at the bottom again.
Here are some things you can do While in a game:
Double tap home button to open guide. From here, one of the easiest things you can do, when narrator says guide, is simply press x to record a game clip. I will explain about that below.
The next thing is, from here you can view achievements. Go down to the achievements tab making sure the game you want is launched. Instead of clicking "see my achievements", press down. You will see a combo box saying locked, or unlocked. If you set it to unlocked, you can see every achievement you've earned in that game. Or if you set it to locked, you can plan ahead for your next achievement you want because it will list them all for you.

About game clips:
In normal guide mode while a game is launched, double tap home for guide. Press x to record a clip. When you do this you are dropped right back into the game so you can still play and then after a few seconds you will hear a beep and in notifications there will be a dvr notification saying game clip recorded.
You can change how long these clips are in settings, all settings, and I think you go to preferences and then game dvr and streaming. There's a weird option called record that records, that can be set from 30 seconds to around 3 or 5 minutes. This will not record your microphone, but it's useful if you did something awesome. So let's give an example.
I just had an awesome battle in Killer Instinct. My game clip is three minutes, so when the match is done, I just double tap home, wait for narrator to say guide, then press x. I'm then thrown back into the match menu and I hear a beep. What has just happened, is the game rewound, recorded the last three minutes of gameplay up to the point where I pressed x. So it's a sort of time travel record, and lets you grab things as soon as they happen.
You can then go to something like xboxdvr.com type in your gamer tag and see all of your clips, and even download them as videos to show your friends, or just share the links to them. Fellow forumight sightlesskombat also knows of similar websites too, I'll see if that person can jump in here and list them.

In summary:
While in a game:
Double tap home to open the guide.
Record game clip: tap x.
View achievements: go to achievements tab and press down arrow until you find the combo box. If the combo box isn't listed, then no game is running.

Hi again.
One more question for the XBox one: How does backwards game compatibility work? It seems like it's an item I can purchase in the store. Or, is it just a collection of games which just works on the new XBox?

Thanks a lot for your answers. Sounds really awesome.
@Malick: Welcome to the forum.
That depends on what you want. Do you want a console with a screenreader which works no matter what country you are in? Or do you want a console, where the very limited screenreader only works in the US? If you want the first option, then the XBox is your choice. The ps4 do have a few more playable games though, including some old playstation games, which are being released for ps4 as well.
I personally like the design of the ps4 better than the XBox one, but that's just a personal thing, and the online features such as multiplayer is free on the Playstation, and it cost on the XBox. So yeah, there are both good and bad things no matter what you choose.

No, Playstation plus is not required to play games online on the ps4. Playstation Plus is a membership where you got games and other content for free or at a lower price.
Does the share menu not work with the screenreader?

sorry SLJ, ps+ actually is required to play online. Try playing any game online without ps+ and it will ask you to purchase it. I've tried this from personal experience with SF V, Guilty Gear and many others. PSN online play is no longer free and hasn't been for at least two years.

I'm sorry. Well, it's long time since I played online then. I did it then it was free. Thanks for correcting me, and I'm sorry for the wrong and outdated information.