If so, when and to who
Yes, early in his career in WCW. Before he got the push and started counting his "streak". Goldberg lost to Roddy Piper in a qualifying match for Piper's War Games team. He also lost to Sting and Chavo Guerrero Jr. in televised matches before his push started.
Yes. Once. It was at a house show against Chad Fortune in WCW in the very-beginning of his career, before he even began televised matches.
Booker T got the closest clean win.
It was a short match on Nitro. There was some interference from Earnest the Cat Miller, but Booker hit his move and got the 1,2,3.