I had a betta fish for about a year before he jumped out of his tank during a tank cleaning and he died shortly after. I've debated about setting up his tank again and getting another, but after about 6 months i'm ready. I miss having a betta fish tank in my living room and talking to my fish while i'm getting ready for work. (dont judge me, i talk to all my animals like they're real children

So, here goes:
I have a 10 gallon tank (with a lid), a filter, and fake plants for hiding. Should i add a heater?
I want to have my dalmatian molly in the tank with the betta, should i add him first so the betta doesn't "claim" the entire tank?
If i shouldn't add a dalmatian molly, is there any other fish i could add?
My first betta was an adult when i got him, but petco has plenty of baby bettas. is baby betta care different than adult care?
What do yall feed bettas? I had regular "betta fish" pellet from petco, is that okay or should i feed something different?
Any other betta care advice is welcome!!!