Umm, you make it sound like you're planning on getting more bettas

I'm not all too sure about how much you know about bettas, and I cant say I know much. But I've been reading on the betta forum they got here ... and they dont make good community fish really. Not that they'll harrass the other fish, but the other fish might nip its tail, and he'll probably not feel too happy. I think he'd be better of in a (small) tank of his own.
Also, you can not keep bettas together in 1 tank. 2 Male bettas Will kill eachother, bettas in a big tank, ok ... but put good diveders inbetween them so they can Not get to eachother.
Also, you can indeed not keep the male and female bettas together, during breeding it tends to be ok, but take her out as soon as possible, seeing as they will more than likely get in a fight together as well.
Female bettas, I'm not sure about ... I think you can keep more of them together, but not a 100% sure