Don't feed anything Freeze-dried to anyone. Freeze-dried can be fed once in a great while as a treat but it promotes constipation and bloating which is obviously no good
Micropellets are fine, you can get the ones from Hikari but if you can get New Life Spectrum Grow formula or regular NLS betta pellets and split them up for your little one. And yes if they are healthy they will actually metabolize food withint 3-4 hours so that's when they should be fed. But also don't feed them so much that they're gut is hanging way out, that's no good. Small quantities but at many times is the way to go.
Frozen foods are good too like Bloodworms, Daphnia, Tubifex worms and so on. Live foods are the best for them but harder to obtain or for me; wrap your head around how you're actually supposed to keep a Brine Shrimp culture going haha.
I also use NLS flakes with garlic in them for my babies as well, don't be afraid to mix it up, Betta's like variety.
And yes moss balls and all other plants are perfectly fine.
And tips for the little one to grow! Do at least a 50% water change every day or every other day. Babys actually excrete a Growth Stunting hormone that can also effect themselves so the smaller the tank, the worse it can effect them. It can also effect other fish as well. So to keep your baby on track, do at least 50% every other day to get rid of that hormone in the water so that s/he can grow properly and quickly!
I had both my baby boys in a split 3 gallon and they were doing well but I switched them over to a 5.5 split and they started to grow like weeds!!!
If you show me a picture I can probably tell you the gender unless it's too young