Allows you to embed panoramas or virtual tours in your blog. Either embedded directly within an iframe, or with a linked picture opening a new window.
Probably yes, because the panorama is either in an iframe, or new window.
Probably yes. You can use the shortcode to point to a directory (containing a default file, such as index.html or index.php) or an individual file in a directoy.
It is advised to link to webpage, a webpage that includes al nescesary files to show the panorama, java scripts, xml files etc etc. But it should be a "clean" web page, that shows the panorama at 100% width and 100% height. (unless you need otherwise)