I know there are some issues like that in TinyMCE/Online Editor that are often difficult to reproduce. If you are able to reproduce those problems, please open the relevant bugs on the issue tracker. Don't forget to be precise enough on the used browser btw.
Ok, the first one is easy to reproduce, I filed a report for it (#018419). The second one seems to be working fine locally. Funny. Will look into that some more soon.