I think I would re-sand your car with 400 before you paint it. My experience with Rust-oleum is it won't like to stick to a finer sanded base. Even thinned, the Rust-oleum is thick paint designed to cover voids well. There would have to be very deep scratches to show through it.

I don't know about the Rust-oleum acrylic, but spraying the standard Rust-oleum says re coat before 4 hours or after 48 hours. Its a pretty thin line between being ready to accept that next coat, and running the next coat. I suggest you start the 2nd (and later) coats in an area where a small run won't kill you (it will be weeks before you can fix the run). I would think the base and the clear coat would be applied the same way, if it doesn't tell you differently on the cans. I would do a minimum of 2 coats of each, depending on your coverage, 3 might be best. With the oil base, you pretty much get done with the 1st coat and you start the 2nd coat. It gets to be a long day. You can't sand the oil base until at least a week later, and then its going to be very wet 400.

You may not need anything to thin it for spraying it, but you will need something for cleaning the gun afterwords. The Rust-oleum is a pita to clean out of the gun.

Please post your results, I've got a truck I will be painting in a couple of months. Gene