SPOILERS -- If you haven't completed Act 1, I wouldn't recommend reading this:

OK so still in Act 1 or Chapter 1 or whatever. Just did the part where you fight Letho for the first time. You have to side with Roche or Iorveth. Anyhow, Triss got stolen away and such. Anyway, investigated, found dying Cedric, and now am supposed to talk to either Roche or Iorveth. My question is...this looks like the tail end of the Chapter. Am I still able to complete the sidequests?

The reason I ask is Troll Trouble requires you to go to Sile...and well she isn't in her room anymore...so...yeah. Thoughts?

The Troll Trouble is partially botch I had to speak to someone else to trigger the completion of the quest. The Poker Dice was botched for me because Einar Guasel disappears.

And the others? I haven't done Endrega Contract either...

I can't remember. You could try Sendler in Lobinden.