For the metal powder/binder compositions. Jewelry metal 'clay' is what this brings to mind immediately. Yes, in fact, what you're proposing with the powdered metal filament+binder, is in line with powder metallurgy techniques used today.
A combination of brass powder and PVA binder worked well for us, we made sheets of the stuff for LOM style printing. Benefits of using PVA is that you can really load up the metal powder and as the water evaporates you get a very dense material. PVA smells horrible when burning the binder out, but it's cheap, environmentally benign, and readily available.