Nobody rototills their whole lawn. I'm not totally sure why. I have heard it stirs up weed seeds? It is probably also prevent uneven settling (even with the roller). I'd expect it to get bumpy.
I always see a bunch of Mexicans digging up lawns with mattocks prior to installing a new lawn.
Think about renting a sod cutter instead of a tiller. That will cut out strips of bad turf and leave you with smooth soil. You don't need to add more top soil. You don't need the roller. Just dress it with some compost and seed.
You may also want to leave the soil unseeded for a few weeks. That way, any weed seeds in the woil will have a chance to germinate and you can easily get rid of them without destroying your little grass seedlings.
I always see a bunch of Mexicans digging up lawns with mattocks prior to installing a new lawn.
Think about renting a sod cutter instead of a tiller. That will cut out strips of bad turf and leave you with smooth soil. You don't need to add more top soil. You don't need the roller. Just dress it with some compost and seed.
You may also want to leave the soil unseeded for a few weeks. That way, any weed seeds in the woil will have a chance to germinate and you can easily get rid of them without destroying your little grass seedlings.