I thought it was the done thing?
Only if you're particularly sad

.
Congratulations, though - looks very nice. Oooh - I see you have auto headlights? If you're thinking you'd like to economise on rubber I'd be happy to swap your 18" Style 37 M-parallels for my 17" Style 66 lesser M-Parallels

. Style 37s - om nom.
In my experience you only need to sand if the lenses have gone really badly cloudy. If they're not bad you could just spruce them up with some Meguires PlastX.
Yes that noisy fan will be because a cheapo aftermarket one was fitted.
Get yourself sorted out with INPA, DIS, SSS and check out your error codes. You may have loads of old ones stored like I did which is mildly interesting reading, but the thing to do is clear them out and see which, if any, come back, then investigate those. Particularly keep an eye on the gearbox for errors.
Check out BMW5.co.uk - good E39 section with lots of hands-on guys, how to guides (even one byme

) and plenty of good info.
Enjoy, oh and this thread is useless without (better than the Autotrader ones) pics

.