I suggest side folding if you want to be able be able to fit a pad to the part of the stock your cheek will rest on. Under folders can be annoying for that reason.
ATI makes a durable and reasonably priced (in comparison to others) T6 that side folds. http://www.milsurpstuff.com/proddetail.asp?prod=AKA3600 I suggest this one, because it will adjust nicely depending for seasonal attire and different shooters.
For a little less money, you can get a TAPCO side folder that doesn't collapse.
Installation is a matter of a pulling out a couple screws, and pulling the stock straight out, with the reverse process to put the new one in. It is about as complicated as putting a fresh lead in a mechanical pencil. Nothing to it.