fraternity rush

So after my freshman year I wasn't really sure what I wanted to do, and felt that going back in the fall would've been a waste since so I decided to take a gap year to do mission work on farms in Zimbabwe. Now I'll be a sophomore at UA (first year here) and want to join a fraternity, but I'm worried about two things, being a sophomore and I'll be turning 21 during pledging (if I get a bid). I was just curious to know how fraternities looked at upperclassmen rushing and if those who did got bids?