X-Men continuity is tricky because so many writers changed in the 90's, many plots were left dangling or changed from the way they were originally going. I believe Days of Future Past was prevented when Phoenix (the daughter of Cyclops and Jean Grey) traveled back in time to the present and joined the X-Men. The traitor issue (the reason Bishop came back in time) was resolved when it turned out that Professor X himself was the traitor, an earlier battle with Magneto left some of him in Xavier's mind, and it warped him, eventually turning him into Onslaught. With Bishop's help, they stopped Onslaught and returned Xavier to normal.

I won't be watching Dollhouse because I don't want it to be run out of order or canceled after one season. Thankfully in this day and age, if it starts picking up steam and is a pretty solid hit, I can easily catch up with DVDs.