Depends on the rooster. Most are just fine with little chicks, some get a little feed possessive towards the little ones. I've only had one rooster like that...all the rest have been just fine with little ones.
Try to resist the temptation to make her leave the nest. She knows when she needs to do so and her metabolism has slowed down for brooding, so they don't need to eat or drink as often as regularly. As Molpet has stated, chickens have been doing this since the beginning of time without our...
Nowadays I only use broody mamas, which pretty much takes care of getting them started right in all ways, but before that and when I had chicks to brood without a mama, I did the following:
I brood the chicks right in the coop and right on the same deep litter my flock has been using...