they go by abrasiveness, or how hard the compound is. always go with the finer one to start with.whats the difference between the 3-4 types?
At least your car is white. You can neglect it and get away with it.
The claybar should get rid of the first two. The last one looks like a deeper scratch and will need a paint touch up.
After you clay THE WHOLE CAR, wax it with a sealant-type wax. I recommend Meguiar's NXT Gen wax.
we had a customer request i use the scratch X, then the NXT stuff (the newer stuff) on his black 2000 mile bently cgt. blah!!!! product sucked ballz. this is comparing it to the stuff we normally use. but its damn good for a store bought product.