To answer your questions about the tame rat you found outside, I was the proud owner of a wild rat that had been rescued & could no longer live in the wild. He had a wheel he loved running on until he got too old (or maybe he stopped running because he finally realized he wasn't getting anywhere.) I fed him mouse & rat food I bought at WalMart & fed him parrot food that contained sunflower seeds in the shell. Since yours is used to humans, you will have better luck than I did. My wild rat bit me 3 times. As far as gender, it was obvious mine was a male due to prominent testicles. As for names, mine was Rattini. I often said if I got a 2nd one, I would name him Ratatouille. I hope you have many years of friendship with your rat. Mine lived to 4 or 5 depending upon how old he was when he was first captured. Some only live 2 to 3 years.