hp for all factory cars is rated at the crank.
in regards to the push on the 2010 models.. sways and links will take out a good majority of it (did in my case anyway) .. it'll never be quite like a rwd car handling wise though. It may better suit your driving style or may disagree with you. Only way to tell is to drive one. If you dig it enough to grab it, change the sways and you'll have a really sweet driver feel along with taking the push out.
From the research I've been doing on the 09+ (not alot of data yet on 2010 but the 09 is virtually identical) .. with just a stage 1 tune they gain something like 30 hp and 40lb/ft tq. Stage II puts it over 300hp @ crank and closer to factory crank numbers at the wheels.
Be advised though, any ecm changes toss your driveline warranty out the window.. but all oem's are like that. If you're comfy with that Idea, tune to hearts content. From what I've read and heard, the access port unit can "un-marry" itself after returning to a factory tune. This might be useful in getting around the warranty catch if something does go wrong.
The newer 5mt is supposed to be stronger than the older versions. I'm not sure on this (not willing to use my own as a test mule ) .. but haven't heard of anyone breaking a 08+ 5mt yet. All depends on the driver and how graceful power delivery and shifting is.
so far from my 2010 and 17K mi of seat time.. as well as having driven quite a variety of bimmers in the past, you'll be quite pleased with the subaru. Its snotty enough to be alot of fun, utilitarian enough to be useful and well I love the hatch so I think it looks wicked too.
Also not going to chew your wallet quite as bad as the "Bavarian Money Waster"