Some website that talked about the Ringworld series said I should definitely read Protector before continuing on with the rest of the Ringworld books. Perhaps the Ringworld Engineers will talk about the Protectors, but otherwise, I didn't see any connection.

It was an interesting tale, though the end seemed really abrupt. I'm learning that this is Niven's style... to have a character or two reach a final conclusion, continue the story as if we all know the conclusion, and then explain it later. It throws you off a bit, but it's an interesting literary style. I'm still left scratching my head a bit at what really happened at the end of the book, but... as I said... maybe another book in the series will explain it a bit more. If not, there's always Wikipedia!