1) I'm thinking Harry and, probably, Ginny, Ron, and Hermione became aurors. This seems logical to me, given everything they went through. (And, the fact that we know Hermione doesn't teach, since she was with her kids at the platform and telling them to send love to Neville). We know the boys wanted to be aurors. And, Ginny seems to want to do whatever they do, plus she's damn feisty. Hermione, however... I always thought she'd end up as a healer, but when it really counted, she was so hesitant with healing magics. But, given how instrumental she was in their overall survival for the year? I'm thinking maybe she took that path too.

2) I think Luna married Neville.

3) You know, probably because Harry wanted some time not being ZOMG HARRY POTTER. And, because, he probably wanted little Albus to have a chance at being just Albus, not OMG Harry Potter's kid. I think he was trying to perhaps give them something he didn't have - just the ability to be a normal kid, not the OMG FAMOUS SCAR kid.