Well that is a tall order... the US aircraft is a little easier as they had a fairly standard scheme through the war. follow this link, in there you'll see some pretty standard sets of paint for different countries for different AC through the war, you don't have to order them but it will give you some names and possibly FS numbers on them for reference with other brands.
http://www.testors.com/catalog_browse.asp?ictNbr=68
After looking at it, for the US sets you'd need Light Gray added to the set as well as Flat Dk Sea Blue, Intermediate blue and Gloss Sea Blue. For the German set to do early war camo, RLM02 Grau. For the British set they are pretty much complete. Be careful and look at the German sets... one is for aircraft, one for armor.
If you have questions about a particular countries color schemes or even ones that are different than the standard ones feel free toc ome back and ask! The best place for specific questions on aircraft is the aircraft forum.
Good luck!
P.S. for NMF I believe Alclad2 to be the best in my experience, others use Bare Metal Foil and SNJ powders with good results as well...