Ponzonik, many thanks for the feedback. All very good points. We are going to start work on an updated extension very soon to bring this in line with the Chrome extension.
To address your points specifically:
1. In the new version we will be loading the panel URL in your current tab, the same way it works with the Chrome extension.
2. The email address being narrower is something we'll have to look into.
3. Toolbar button is something else we're going to try and do as many are reporting the icon in the add-on bar disappears occasionally.