You could try a harness and leash. Stay out there with him so he won't be alone. I used to do that for one of my cats who really loved being out side. I was able to let her enjoy her self and stay with her to watch her.
It sounds like it is infected. That's whats causing the odor. You could put Neosporin on it and bandage it. I don't think your cat will like the bandage much tho. They don't like anything on their paws.
It might be a good idea to get your cat checked out. If the paw is infected they will give...
She probably saw another animal out there and was reacting by making those noises.
I once had a cat that was an indoor cat. When she saw a bird or squirrel outside her mouth would chatter like but no sounds came out. I thought it was funny to see her do that.
I'm sure your cat is fine and is...