You really should wait a little while for people to answer instead of posting the question twice. I'm not sure what he is but he's a cute one. He looks like a medium small dog. Maybe he has some beagle or dachsund in him. You might want to take his collar off while he is in his cage-dogs have gotten them caught and strangled.
How big is he? He has the same coloring as my Max but Max is 65 pounds and his ears stand up (sometimes anyway but one is kind of sideways) Nobody has ever been sure what Max is either and even my vet can't hazard a guess other than probably having some shepherd in him. He was about 2 when I got him at the Humane Society. Also a guess on the age. I think that both Maxwell and Max were puppies born to a mixed breed Mom and there's not a lot of any one thing in them to identify. Just a lot to love because they know they are lucky and we are lucky somebody was stupid enough to give them up.