Hmm, best advise i can give is not to DIY yourself without someone experienced to guide u along, especially if u're planning on using abrasive cleaners/procedures.
As for your scratch marks, its not the length that matters, its the depth....
Swirl marks can be dealt with by using a light abrasive but experience is needed or u're just gonna make things worse. remember, as long as the damage hasn't gotten through the wax to your paintwork, there's still hope for salvage.
If u decide to seek professional help, u can check out my thread here:
http://bmw-sg.com/forums/viewtopic.php?t=3084&highlight=
we deal with many BMWs and we're offering discounts for BMW.SG members.
anything i can help u with, feel free to ask/PM
cheers
