We are aware of the problem where you delete some text, and end up with the style from the previous paragraph (eg heading). Will certainly look to fix this as soon as we get some time.
We are not aware of the issue with collapsing. I guess you mean the note becomes the wrong size, correct? Hitting return will usually fix a glitch like that.
Do you have some steps we can do that will trigger this problem every time, or did you just see it once?