Hi...I've never had to plant grass before.

We moved a 6x8 sandbox last fall, so there is a spot that is bare
dirt. How finely (and deep) do I need to till the spot in order to
plant grass?

Also, we had a large (20' x 20') strawberry patch. I mowed it down
last year, and kept it mowed so that it is weed/grass, but not lawn.

How should I prepare that spot for planting grass?

And finally, I have about a dozen patches of that nasty "clumpgrass"
that I want to get rid of. These patches are only about 12" in
diameter. After I dig out the clumps, do I need to work up the soil
before planting grass? Should I use seed, or "paste" for these small
patches?

Thanks!