When I was trying to figure out the correct csid for a quest, I tried the @cs "" command but it got stuck at the same cutscene no matter what number I put in.
This NPC had 27 csids which makes it difficult to find out the right one
It depends. If the cutscene neatly closes itself and you let it finish, then no, @release isn't necessary. If the cutscene is meant to be used in a very specific context, or you interrupt it somehow, @release is pretty much required, and your camera will potentially be a mess.
Also, @cs does not require quotes, if you were using those. @cs 17 is all that's necessary.