I never did play Quidditch and I wasn't a Prefect or anything like that. Too focused on my own studies. I did go to games though, went to World Cup once with my dad. That was alright.
Transfiguration and Ancient Runes were my favorite subjects.
As far as job, you want something you're going to enjoy doing in any case. I used to be an Obliviator, but that line of work wasn't for me. I didn't enjoy it, so I moved to Unidentified Magical Objects, and enjoyed that so much more. Not sure if that translates to a specific job here on the island, but we'll see.