We bought a dremel to do his nails and he absoutely hates it. I let him look, snif and move it while it was not off and he just backs up. I turned it on and he ran away. So we will us the dog clippers for his nails, those seem to be working.
No idea, sometimes with mixes it's so hard to tell what the parentage is. I do think that your dog's head is a bit more refined than many of the pit mixes i've seen.
I agree with the others that although he seems to have Basenji in him - his head is def. not Basenji.
As for the leg I'd have it amputated if it troubles him - He'll cope with 3 legs I'm sure, but certainly consult a specialist first. Please keep us updated.