If anyone is in the Washington area before March, the Smithsonian currently has the exhibition "Clash of Empires: The British, French & Indian War, 1754-1763." It's been making the rounds in canda and elsewhere in the US.
It's a nice overview of the north american war from all sides. They include a fabulous diorama of Fort Duquesne (i'm guessing about 6-10mm scale.) and another one of Braddock's defeat. same scale.
Zvezda are really rather good with their modular fort designs. Better buy the wooden fort rather than separate bits - cheaper.
As for any internal buildings made of stone, you may have to visit a model railroad shop for scratch-building materials such as stone walling etc and go from there.
good suggestions from you all. i'm really looking forward to this project. as it is, i'm painting a lot of ARW figures that i put on backburner because of napoleonics. the imex artillery sets and italieri indians made me interested in the period again as a possible wargame. thanks again for the info people, and happy new year as well. (i'm off the forum for seven days.)