The Dwarf clans are the first phase of my plan to do something of this sort. I will do other separate groups within races as well. For instance I think I should explore the divide between an "Insider" elf and an "outsider" (I have no better name for them atm).
Humans irl tend to be very different if they are military or bureaucracy so I could make a conflict there.
Elven stuff should be quite fancy. A katana is the epitome of a "fancy" sword. This sounds like a pretty good idea.
You basically hit the nail with most ideas. The Miserly goblins would probably be very good at booby traps (Like the explosives you mentioned) and unconventional weaponry (They wouldn't care that a golden sword is worse than a steel one).
The Orcs you mentioned were 100% correct but I'd like to add that it should also look like it was made from the other races' scrap metal.
Not sure what you mean by "med-tech" but I see Trogs as the behind the scenes con-artists of the Orcish "nation". They'd probably have a bunch of thugs to do their bidding prefering not to get into combat themselves.