(1) Paint often persists for decades in the desert. Paint is slightly elastic, plus large flat faces form wind shadows, which reduces the abrasive impact. So scour the paint, but it should be totally absent only on sharp edges. glass would be frosted, though.
(2) Right. Things rust because of the dew, whch can be quite heavy. Particularly burned things.
(3) Rubber would be pretty much crumbled away, except for heavy items like roadwheels. They would be cracked and pitted.
(4) Most of the areas fought over in North Africa were reg or stony deserts, not the ergs or "sand seas". (These are Arabic words which are used to decribe types of desert terrain). You would probably also have undrbrush and grasses around, since any high-standing wind obstacle tends to trap moisture and seeds, and a thin soil develops. Much of the "desert" was not what the public would generally call desert, particularly in Tunisia where the Tigers were deployed. It was more like farmland, as in the Sejeanan Valley.
This is based on working as a geologist in several deserts about the world -- and finding old vehicles therein.