Wheels is a big choice you'll have to spend hours deciding, like I did a few weeks ago.
If you want to play safe (and cheap), go for Audi/VW look wheels, which always suit the Golf.
The best looking wheels however are 16" or 17" BBS RS split rims, but are very dear I'm afraid (Porsche alloys look sweet too)
A recommend company for replica's here with often next day delivery:
http://www.autoalloyz.co.uk/vw (site gone offline since I posted, keep trying)
Go for the Audi S Line over the similar RS4, as side by side the S line's look twice as good.
205/40/17 tyres will be okay, with lowered suspension with mimumum 'scrubbage'
Decent split rim look, 16's, look good, such as BK Racing range which are cheap, but remember multi-spokes = harder to clean!
I think Eibach do good springs for 45 - 50 mm drop at £120 from AwesomeGTI, etc. (who also do BBS RS style wheels)
Great if your standard dampers are in good nick, not high mileage, if not, you'll find a massive difference with new sport dampers to suit.
