I'm going to take a shot in the dark and say female but I think it's to early to tell... As for the shell I am not experienced enough with the species to give you a good answer and let the more experienced members help you out with that.
I was 13 when I got my tort. However, me being in high school, I haven't even thought about having to give him up because I am 14 and don't really worry about those things. Anyway, if you can properly take care of a tort and are willing to make the commitment whether it be for 10 years or for...
I would recommend a large wood table with deep coco coir for substrate to dig in. Many plants and hides a ceramic plant saucer for a water bowl and a tile for food dish