Unfortunately the old feedbacks can't be deleted, we've tried before after we switched to the new site. Since they aren't actually linked to an account, the site can't work with them.
As for the PM thing, that is odd if it's showing and you haven't sent any. It's a set limit per 24 hours, and does include group PMs (ie 1 msg to 5 people counts as 5 msgs). All I can say is hopefully it will clear itself up.
ETA: I was thinking more on the PM situation and realized that your multiple report PMs are likely included in your PM count. So that's why your limit is used up (4 PMs each going to multiple admin). It resets after an hour, not per day.