Yes, both are possible. Here are some examples: "Guilt without regret" would happen if you did something that you knew was wrong but you are glad you did it for some unforeseen reason. For example, you might say something mean to a friend at a party. You hurt their feelings, so you feel guilty. However, because you hurt their feelings, they stopped talking to you. You were then left alone at the party and a person you hadn't known came over to you and started a conversation. That person later became your best friend. "Regret without guilt" would occur, say, if you attended a university that you later realized was not a good fit for you. You are sorry you didn't choose a different university but therre is no reason to be guilty.

For the last sentence I would say “or DO regret and guilt mean the same thing?” Regret and guilt are very similar. if you feel guilt over something, it’s because you are disappointed with yourself. Regret is less specific, and usually focus on a moment you made a “bad” choice. An example- I regret being late = I wish I had not been late I feel guilty for being late = I feel sorry that I was late

This is a deep question, and would be a fun debate I think. But I would separate them because they are different. You can feel guilty of things you've done that you WOULD DO again, but regret is something you feel about actions that you wish you could go back and change. Does that explain the difference to you?

I have always heard “put them through”, if you’re referring to a call system. I’ve never heard someone use pass in that way, though I can’t say it’s necessarily wrong.