Well, bless your heart for taking that baby in!
I wonder who could have and why someone would just turn out a little poodle...that poor baby!!
First, have you taken him to the vet to get checked? I would to just make sure he isn't carrying something yucky that could be passed on!!!
Second, I am a true believer in harnesses. I never attach a leash to a collar on any dog...not even my big labs! So, definitely, put a harness on that baby when going for a walk....it is a good idea to have a collar with their tags on it though...if you are keeping that baby...you don't want it to get lost either!