Have you asked him why he is misbehaving at school? Maybe start talking to him about his day will help. The reason I asked this is because my nephew did the same thing when he started school. We found out that the other child that was acting out with him, he thought was cool and made the other kids laugh and he liked the attention.
I was a kindergarten teacher for some time. School just started, he still has to adjust to the environment, but at the same time he needs to be accountable for his actions. I agree with the idea of taking away activities, games that he enjoys. Just don't ignore the situation and it sounds like you're not.
As for the teacher, I know you want to hear daily reports, but sometimes not so good reports can add to the frustration with your little one as well. Discuss the not so good and the good with your child. No parent or child wants to hear the teacher give bad reports about academics or behavior.
Just be consistent with him, he will get the picture.