Wanna check with all, if i want to play songs off my thumb drive...wat are the methods of doing so without affecting music quality?

Best if there is a solution that syncs with the control buttons on the head unit/steering wheel as well...any solutions apart from changing the entire stock player?

White has been hard for me to maintain while i find the aluminium really appealing on the m3, captures light and reflection more attractively.
Grats! 
How about taking the car for a spin?  Anyhow, if the criteria meets your valuation then why not?  There is only so much "convincing" we can do for you, i think it's more about you convincing yourself    Just don't forget the warranty period is almost over since it's a 2009 car.  So the best on your purchase 
If you can accept it, you could use a FM modulator, there is a discussion here:
FM Modulator