I highly suggest you don't attempt to spawn your fish based on the questions you asked here.
Bettas are not livebearers. They do not get pregnant. The female fills with eggs, and during the act of spawning, they are fertilised by the male. The male then puts the fertilised eggs into a nest and tends to them until the fry hatch and become independent of him.
The female cannot be kept in the same tank as the male except for the act of spawning. He will attack her if they are not ready to breed, and he will chase her away and potentially cause serious harm, once they have spawned and he has eggs to defend.
Betta splendens can produce hundreds and hundreds of fry with each spawn. Some breeders will remove the male before the eggs hatch because many males will eat the eggs. The majority of breeders will remove the male from the tank once the fry are free-swimming because there is the risk he may eat them.
Males can be kept with their fry long-term, but this isn't something that is frequently done.
As mentioned, the female cannot be with the male and the fry as he will attempt to hurt her, and she may also eat the fry.
Breeding bettas is a massive undertaking and not something I'd recommend for someone who just purchased their first betta. If you are serious, check out the breeding section of this forum and really do your research.
It's not just throwing two fish together and letting them raise their fry. Betta splendens are a highly aggressive species and this process can very easily end in serious injury or death.