is it possible to rev the start line: like this:

and start where the red mark is

Yup. Place the start by using the 's' key. Of course you can only have one so if you want to move it you'll have to grab the old and press 'm'.

grab the old and press m?

Hit SHIFT+U to open the layout editor. There you will find a land of mystery and adventure.

By grab the old one and press m I mean press its little yellow box - that'll 'pick it up', then you can press m to move it somewhere else.

No, you cannot reverse the start. Im pretty sure your talking about reversing the start (EX. BL1, BL1R) If you place a green arrow going the way you want, only 1 person will come out on the arrow, so the answer is no, you cant change the way autocross starts

Quote from imthebestracerthereis :

No, you cannot reverse the start. Im pretty sure your talking about reversing the start (EX. BL1, BL1R) If you place a green arrow going the way you want, only 1 person will come out on the arrow, so the answer is no, you cant change the way autocross starts

although i think you may be able to change the cfg file to do it... i dunno.