>>> The window appears half outside the browser window, so you get scrollbars!
That's because it installed on right side of the page and that is not called buggy. It is up to you to position it on your website. Joomla is flexible in term of its module's layout position

- In Firefox, other flash modules (like the Myibook network) lay on top of the window.
That is called Banner and it is an image (not a Flash)