Yes, he is a normal sized crow. In his tengu form he can not fly. He can sort of glide, but it's pretty limited, he wouldn't even get a 1:1 glide ratio in that form, he's just too heavy and awkward.

If he had access to the materials (molds for shell casings and the bullets themselves, metal, gunpowder, a reloading press) and some time he could conceivably make more bullets, but that's going to take some serious time, he won't be making them any time soon.