Wotcha and welcome - 2.5 gives slightly more oomph lower in the rev range, both similar at mid to top end.
Petrol consumption is all down to your driving style but both can return 30mpg on vpower.
auto v manual. Again I would say this is down to where and how you drive - I find the auto box on my current Scoob frustrating when pushing on a bit as it hangs onto high revs in both normal and sport mode + seems to spend too much time thinking about what gear you are in when you floor it off an island or to over take meaning a dramatic pause before acceleration. That aside the box is smooth through the gears but dont buy an auto of that year if you enjoy 'driving' your motors