Don't roto till the soil. Don't apply topsoil to overall area unless you spread it to a depth of 4 to 6 inches to entire area. Use topsoil to fill in any low areas. Do kill all existing vegetation in area to be reseeded. Weeds and other vegetation should be watered well prior to application of herbicide.
Healthy weeds die faster.
In the fall, allow 3 to 4 weeks to retreat some weeds that regrow after initial treatment. Do rent a seed slitter or verti-slicer. Most machines come with a seed box. Do freeze your seed overnight. It can even stay frozen until you're ready to apply.