Congrats on your new pup!
I'd start with feeding twice a day. Our dog won't sit and eat when you put a bowl of food out, so we switched to leaving the food out all day. He snacks a few times a day.
As for what brand, I'm of the belief of "no fillers," ie: corn, wheat. Dogs can't really digest them, and for small breed dogs, it can make them heavy. It also means they go to the bathroom more since they aren't digesting all of their food. I'd definitely use a puppy version of whatever food you choose, so that your dog gets the extra protein, at least until 10-11 months old. We use Halo and really like it.