I own a Legacy Spec B 3.0r. Auto it's a 2007 face lift ,with close to 60k, I've also owned most other legacy sand engine sizes, I find the 2.0 ok , 2.5 a little better, but heavy on juice, running cost no better than 3.0, the first 2 don't put a smile on my face, the early 3.0 slightly down on power compared to the face lift 2007 on, which also get SI DRIVE Gearbox ( 3 modes of black magic ) to answer your questions.
1 Autobox fantastic never had a problem
2 4wd the same
3 no buy a 3 later ,only pop and milk come in 2 litre and 2.5 litres as far as I'm concerned, running cost not much different, perfomance and torque are
4 heavy on front brakes
5 not yet
6 never had a problem
7 yes do all mine myself but I do work in garage
8 got sat nav head unit, and parrot kit which links to iPod and phone
9 I get 25 mpg combined (I don't hang around) can get 32 mpg on run sensible driving
10 chain on 3.0 not sure about 2.5
Great car you can see mine ( the actual car) on fifth gear, on you tube there is a link on here somewhere, I'm sure Gambit the tech wizard will find it for you, Good luck with your search, double you money and I'll consider selling you mine Lol