There are lots of charities in Europe taking care of Spanish dogs, as they are treated pretty badly - especially the hunting breeds (sighthounds), like podenco (comes in all sizes and colors) and galgo (a little smaller than a greyhound).
Ohhhh...... what a sweet cutie pie!! He's going to give you tons & loads of love... along with testing your patience from time to time but... that's what all kids do ~ whether they've got 2 legs or 4 .. right? And yes, pictures all along the growing up stages (even if it's one where he gets all the stuffing out of a couch pillow) Very lucky you are! Thanks for sharing :)
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.