At the beginning I ride with this big "elevator" up. But how can I get into the vent? its too high for jumping

Go through one of the side vents on the wall. You can open these with your lightsaber.

So far, so good but what next?
The vent ends in that huge, dark room (/hall/however) with nothing in range to jump on. What now?

@Slowhand: The vent YOU where talking of, is just a secret area. You have to proceed through the door under the orange light. By moving near, I triggered the opponents behind to open it. Good luck!

Originally posted by crying_lobot
So far, so good but what next?
The vent ends in that huge, dark room (/hall/however) with nothing in range to jump on. What now?

Um, I have no idea where you are... describe your surroundings and the last thing you were able to do...

Sorry for not having described that place any better but my english vocabulary is not too... extensive.
But I found your answer to my problem anyway (here (http://www.lucasforums.com/showthread.php?s=&threadid=35823) to be precise)

Btw, having you answer all these questions is really great! :)