fpr, you asked: Did I hear right many weeks ago,
that the cop and his victim knew and had prior personal antagonisms with each other...???

The two both worked security at a club and a day or two after the Floyd killing, a third person who worked at the same club came out with the story of them having a beef with each other. However, this man quickly recanted the story, saying he had confused Chauvin with another employee. There is actually no evidence that they ever interacted on that job.
Someone from management did say that Chauvin was not very good at security. He did not know how to de-escalate situations, which is always the first thing any bouncer should attempt. It was said that he often seemed nervous and quick to call for assistance, especially when dealing with people of color.