Reseeding and raising damaged lawn
 

Hi,

I had started off with an already tidy and uneven lawn. I then had building work carried out, garden dug up for a new sewer, heavy machinery driven all over it etc.
The lawn was always considered to be a little low compared to the driveway beside it. So I want to cover the existing grass/vegetation with new topsoil and bring the level up by at least a couple of inches then reseed.

What do I need to do to the existing ground before covering with new topsoil - Kill the grass with chemicals? Use a Tiller?

How should I calculate the amount of topsoil required and how best should I level it (it's on a slight slope)?

Any other comments / advice would be appreciated!

Thanks