The cere of the male is always smooth. In a hen ready to breed, the cere will become rough, no matter the color of the bird. In the wild parakeets nest in holes in trees. In captivity these birds nest in boxes about eight inches square. Don't waste your time and the birds by trying to force them to nest in a finch basket.
Parakeets have up to eight babies.
Ma and Pa keet, and all the babies, must be able to fit in the nest. If you are not interested in breeding your birds, the sexes don't really matter. Parakeets are almost always friendly with each other if all placed in the cage at the same time. Just use common sense and allow the birds some elbow room. Don't over-crowd your birds.