Your DS sounds like a bigger handful than my DD, but this may help you anyway. I couldn't get her to stay in her room for quiet time either until I taught her to look at the digital clock in her room and when the first digit is 4 then she knows quiet time is over and she can come out. It gave her a definite end time to look forward to instead of thinking she was just at my mercy. The first time I did this she didn't quite get it (turned 3 in January) so when she came out too early I spent the rest of the time in there w/her and showed her the clock turning 4 and then we celebrated that quiet time was over and we could come out of our room now. The clock thing has been working really well for me for a couple of months now.
If she makes a mess - books everywhere or the one time she emptied every single dresser drawer! - then she has to stay in there until we get it all cleaned up together. If it's a simple mess like books that she can put back herself then she has to do it herself. I don't keep things like paint or crayons in her room so I don't have to worry about that. The worst she'd done besides emptying her drawers was tearing some books. So she loses those books.