205/50 tyres will look crap. End of story.
15inch wheels came on these cars form the factory. Think VW knew what they were doing.
Get a 3mm spacer, you wont need any new bolts, use the orignal ones, that will clear it from the carrier.
As for tyres, fit whatever you like and can afford, but going for a lower profile, maybe a 195/45 will make them look a lot better, and will only affect your speedo by a few mph, which doesnt really matter as speed cameras have a tollerance, and you will also know that your speedo is slightly out.