Like Ruso said, all good places to start. Also you still some time on the original warranty if I'm not mistaken (until 60k/6years or is it 5?)
The whole bs about the 5MT breaking is mostly from people who not only don't know who to drive but also abuse the living piss out of the car (even stock) and wonder why things fail. These rumors were mostly about the 02-05 (more so the 02-03 but blah blah I own one and psshhh...drama), and those who break them are constantly launching, granny shifting, and other abusive driving styles are the real factor. You can ruin the STi 6MT too, a buddy is complaining about his syncros going under 100k, but he's not the original owner and he doesn't rev match and just granny shifts so you can see why the syncros are going lol. Just don't beat the piss out of a stock vehicle and you'll be fine.
If you want to get a reaction from your father in-law, next time he wants to say something about reliability...ask him about the Corvettes and not only the automatics overheating and failing on the street/track and Chevy admitting to it, but also ask about the dry sump oiling system failing and seizing up the engine in under 15k miles on a stock vehicle
I went to visit a buddy of mine at the dealer he worked at and they had 17 still waiting for new engines within the first 3 months after they came out.
All in all, the wrx can do pretty much whatever you throw at it, if you're smart about how you go about the situation. If you want more power, go forged and allow the engine to heat cycle once or twice before driving. If you want the 5MT to last with LOTS of power (above 350whp) then stay away from ACT clutches (the XTSS kit is known for blowing master cylinders/TOBs as well as introducing massive amounts of shock load to the transmission), other than that you can always get blast plates but those are more for above 400whp/daily launches.