I have reread your post, if I found out that DS school was handing our negative points, of any sort, no matter how they put it - I would go ballastic, exactly is if he was losing play time.
Positive rewards is way more effective for children, negative points, 4 years old first weeks in school - makes me so ANGRY on behalf of these children.
On the teddy note, can I say, I know that there is a school of thought that says that you shouldn't say a punishment you don't keep, (and I don't think 4 year olds should be punished), but there is nothing wrong with saying "daddy and I have had a think and we think we were wrong to threaten to take away teddy, it was a mistake". Going through with it - especially if it made you cry - was wrong!
Do you want him to learn to behave because he wants to be nice or because he is scared you are going to take something he loves away. And it is good to teach them it is ok to admit to a mistake or being wrong, that even grown ups aren't right all the time.
There is a fantastic website if you are interested - AHA Parenting. here if you like their FB page you get bite sized chunks pop up.
I find rough housing really effective with mine here
We have it instilled in us that we want our children to be "good", to "behave", to "co-operate", but they are still babies at 4. I want mine to want to be kind because it makes them feel good to be nice.
I am not perfect, I shout at them at times, I lose my temper (like I did last night with DD when she wouldn't, just wouldn't go to sleep), but I apologise, the next day I told her, mummy was wrong, mummy was unkind and mummy feels sad because I know I shouldn't have shouted at you. Later on at bed time we talked about going to bed, but it was way more important to me that she knew I had made a mistake and no-one has the right to lose their temper and shout at her.
Gentle Parenting is a different way of parenting, I have heard it called lazy parenting and the world has this idea we let our children run riot, but it takes a lot more thinking to parent this way.
That was very long and I know a lot of people dismiss it as hippy nonsense, I just thought you may be interested - I am not saying its the best way, or the only way, just because it works for my family it may not work for yours, - so I hope you take it in the spirit it is intended.