I've owned both MK5 and 6 (gti) Service schedule for the DSG box is 40k though many overlook this so check the history - costs 180ish for the service (Dealer)
Neither of mine missed a beat. If you're worried about repair bills, purchase the named component warranty from VW.
You'll find in standard form they perform well in drive mode and would rarely if at all need to use S as pressing the gas fully in drive will utilise the max power available. ~30mpg is achievable but you'd need to sustain sensible driving for some time, you'll find consumption floating around 23-28 with mixed driving. (applicable to both models)
No knowledge of software updates, but I'd be weary of this if you do decide to purchase a warranty package, as above, you may be satisfied with these being standard.
I understand that the ed30's are quicker more hp, I've no experience of these - and you'd be better off mapping a normal gti, instead of paying the extra for the edition models, if power is all you're after.