or would it be boring for some of them because they know so much about it? would they get any fun out of it?

doubt that they don't, I can imagine them making [censored] mods with the creation kit right now.
/sleeeeeptime

I always wondered this too. Is say prolly but I doubt the bug testers do lol

I've read multiple places and seen a few interviews where they say a ton of the staff still play it even after hundreds of hours.

*their

Game developers tend to work on a small part of the game, it is doubtful that few of them experienced the whole game during development. So, I can see them playing the finished product and it being somewhat new to them. For example, the cave dungeon team may have never been inside a Dwemer Ruin during development, the people making cities and the terrain may have never done any quest development or NPC work.

I bet they play the 360 version.

I heard they rushed Skyrim out so they could get back to Morrowind. Something about "smarting up."