Feeding my newborn.

An

I think I decided I want to both BF and FF. I have a few questions though. I probably plan to FF during the day and BF during the nights. Do you think it would be hard on an infants stomach? And also do you get to pick which formula the baby is on (obviously if it doesn’t mess with their stomach of course) or do the nurses kind of just give them what they have? I want to use gerber formula.