Welcome mate. Nice choice on car, GC8 all the way
I bought my wrx when I was 19 also, it's good fun isn't it? Just don't act like an idiot or you'll end up wrapped around a pole. Everyone judges because we're young, so don't give them a reason to say I told you so
Plenty of mods to do and plenty of threads about them. Use the search function to find some. I'm sure after reading about what others have done ,you'll have blown all your money in no time
I did.