Yes, I see.
If you don't specify any default value, false is choosen. But I will fix this issue.
Wrong. If you do this you will have problems to edit your element and see it to true when it is to true.
The defaulting is twice :
TODO : If you want to modify the defaulting :
In the table file, in the check() method.
In the item model, in the _initData() method.
The difference is that the check() method is the last fallback test (absolutly secure because always called)
_initData() is for prefilling the item in the forms. (when id=0)