Common problems

Hi everyone I am possibly about to buy a 57 plate 2.0 Tdi 170 A4 avant s-line but have been looking online and hoping to clarify something and receive any other helpful advice please.

Main issue I have been reading about is the oil pump/balancer shaft problem. I get the impression it only affects 2005-2006 engines so should a 2007 engine not have this common fault?

Also the car has 90k on it and I currently have a 2006 seat Leon 2.0 tdi 140 with 85k on it and just had to get gearbox reconditioned, new clutch, flywheel, rear anti roll bar and all new rear brakes. Should I expect similar problems with the Audi or is it uncommon to have that sort of stuff needing done at the current mileage. 

Any other positives and negatives would be much appreciated. I really like the car but need to be sensible about it and if it's likely to start incurring issues I mite have to think twice.

thank you in advance