Sorry for answering so damn late
1) Differences are rather subtle - the "new" cinema mode includes some AI tweaks to make both fleets act aggressively. The old script didn't really take advantage of what would have been the player fleet otherwise and only assigned orders to the other fleet. Doesn't make a huge difference, though.
2) Yeah, timer(StopAutoCamera, 600, 0) is the correct one. It's set to 10 minutes (600 seconds) by default, because I needed to set
some limit on how long to disable the GUI - otherwise the game might crash on hitting ESC during the battle. I didn't want to set it too high, since the game tries to fast-forward to this point in time when hitting ESC during the battle - and that became annoying with much higher time values.
3) I'm not actively working on a new Skirmisher right now - sorry, don't have the time and the old one still "works" (well, mostly), so there's only limited need for that. I'd like to work on it, but I gotta set priorities