I'm very new to this, so I have a few questions.

Will this be big enough for four of them? This is as big as I can go for the moment.
Another housing question: would it be OK to get 4 of the same sex? Does it matter which? I really don't want babies. I've read that if I just don't provide a nest they won't have them, is this true, and in that case would it be better to get two pairs?
Thanks so much!