I can see why someone would think there was Terrier, but I'm not so sure about Basenji. (The only way to know for sure is to do a DNA test.) Both of your dogs look very similar. What breed, or mix, is the older one?
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.