Lots of info on the net on the ED30, just been through this decision myself.
There are lots of road tests on the Edition 30 ( Auto Express, Pistonheads etc )which were written when the car was launched, these explain the differences.
Some cosmetic, main changes are to the engine components ( larger injectors etc ) and larger turbo ie its quicker !
Manual or DSG is down to personal preferences.
I spent about 3 months looking for the right car, considered a GTi but decided on the Ed30 as it is that bit extra special and should hold its value better.
I get 28mpg around town and 35 mpg on a run in my ED30.
BTW Its a great car.