Batclaw pulls enemies or objects toward you. I don't remember what GLHand does, but it might be similar? Trap is supposed to keep enemies stunned for a few seconds or so.
In Mario, most of the items appear on the top of the brick after you hit it, so to take it, you then have to go above the brick and find it. They take effect as soon as you touch them; the only thing that requires further action is fireballs (from flowers).
Not all pipes are enterable. Usually, if you have 3 pipe tiles in a row, you can climb down the middle one. There are a few smaller pipes you can use, mostly single-wides in warp zones. and there are a few levels that have horizontal pipes at the end, such as 2-2. But the general rule is, if there is a center, that's the way through.