Is it recommended to install this new beta version on top of the released version (not release candidate)? If not, can it be installed side-by-side? Do we need a new key?
I second that, it sort of makes me a little nervous installing a beta over a production item. Especially when the production version works nicely...
I was worried also. I took the plunge and followed the install procedure looking for a way to install it alongside the old version. I couldn't. It upgraded the installed version and used the same key (I didn't have to put hte key in again, it just used the old key). On the bright side it works fine and I really like hte cohenence feature (only reason I upgraded). Hope this helps.
You can't install multiple versions of Parallels side-by-side as they include kernel extensions and there can only be one copy of the kernel extension installed at any time. (Parallels could rearrange things to make it possible but that would almost certainly be more effort than it's worth. And, it might still technically not be possible depending on the exact nature of their kernel extensions.)
Somebody asked basically the same question in another thread, see http://forum.parallels.com/thread6931.html for an additional suggestion
