Yes, you will need some adhesive to get it back together. I don't think anyone has been able to source the exact kind Apple is using, but some reasonable alternatives can be had. Look for the posts by R.OG in
this thread for some details he's been providing lots of hands on experiences taking apart a 21", very useful stuff.
As for what SSDs, the top of the pack right now is the Samsung 840 Pro. Great speed across the board, and Samsung's reliability has traditionally been pretty solid. There was an issue with the pre-release firmware that some reviewers got, but all the drives shipped to retail have a fix applied, no firmware updates necessary. The 840 Pro does come at a bit of a price premium it's around $260 for the 256 GB, whereas other top choices such as the M4, 840 (non-pro) and 830 seem to be in the $180-$200 range.
The non-pro 840 and the 830 are both strong choices, I'd rank the M4 slightly below them, but still a pretty top notch SSD. The M4 may have more of a price advantage if you're looking at drives in the 512 GB size class.
