Well, if it was in tunisia it is most likely going to be dusty and battered. For wear and tear on the paint job I use a #2 pencil. Make scratches around hatches and places that, well, might get scratched. Make sure the pencil is sharpened, you can also use a mechanical pencil if you prefer. For dust you could use pastel dust or those MIG weathering powder (I forget the correct name). Alot of drybrushing would be good too.
For the base, I have built 2 dios in 1/72, the only thing is different is that you have to scale things down a bit. For example, dont use as much celluclay or plaster whatever you use, and make sure the sizes of the rocks are not too out of place. Just remember, that no matter where you are there is some kind of foliage. For shrubs, I use the same materials as when I do 1/35, just alot less of it.
If you need a tank crew Prieser makes one with a whole buch of figs. Good luck with everything!