Read the sticky in this forum about timing chain tensioner. Loads of info in there. I think some 2011s are affected, yes.
Watch this video about buying a Mk5 (most is applicable to Mk6 as well):
https://www.youtube.com/watch?v=dKWUu0HU9UUWatch this video about buying a Mk6:
https://www.youtube.com/watch?v=jkjtW4FfDns&t=164sCan't answer the town MPG question as I don't use mine for that very much!
The manual is fine as a daily. Clutch and gearbox easy to use. I wouldn't call them nice to use. But fine. No issues with getting into any of the gears at low temperature or anything.
I haven't got much experience with sports cars, but I would say the stock suspension is on the comfortable side of sporty. My Honda Civic Type-S I had before was way more crashy.
Factory sound system is actually pretty good. There's an upgraded one called Dynaudio, but even the standard one is pretty good. I fitted Focal speakers and a sub in my last car, but I'm not going to bother to meddle with this as it's fine. The RCD310 head unit is pretty bog standard, though. I upgraded mine to a RNS315 (~£200 on ebay). Some come with RCD500 which is better.
Parking sensors were a £435 option on the GTI but a lot of them have it. Oddly cruise control seems much rarer even though it was only a ~£230 option. But you can retrofit cruise control if you want that.