1: You'll get lots of recommendations here. Imho necro healer or necro druid is the easiest combination to play since necros have a kick arse attack spell (iceblast to the head is fairly lethal), and can use summon bones to effectively get an extra pet. Choose a race like elf who have good starting intelligence too.
Bare in mind though that this will only mean your first character and your next two might be unlucky picks, eg, you might get stuck with an ogre mage or a gnome fighter.
Generally assassin goes well with any melee class (especially brawler imho).
Just remember to never mix magic and technique based jobs since you'll end up with a character weak at both, oh and avoid adventurer and thief. Generally stratogise on the basis of killing your enemies asap, so don't put points into armor skills and you should do well.
Also, while it's tempting to stack up big technique combinations like dhaving a fighter assassin doing flurry sneak attack, bare in mind that'll affect your turn order so take care.
2-3: X is examine for items and enemies, though ALSO FOR ITEMS THE C OR COMPARE KEY IS VERY MUCH YOUR FRIEND.
Observe is actually a wanderer's skill and is used to learn a few techniques from enemies, but very specific enemies, as a hint, try it on dungeon creeps or on bosses.
Answering these questions actually make me think I should install entombed on this machine myself and give the game a try.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)