Porting an App to a Browser Plugin - Info?

Hi all, I’m new to the whole browser plugin stuff but have been asked to port an app to one so I was wondering a few thing about the feasibility of this.

  1. Is everything that is possible in a desktop Juce app possible with a browser plugin? By this I mean things like hard disk access, audio api’s, third party libs etc. or are there limitations due to some sand-boxing? Does the app effectively run natively but use the browser as a main window and message loop?

  2. Are there any performance sacrifices? Is this like a virtual machine where memory operations have to be transferred through a virtual mapper or again is it all native?

  3. What is the current platform support like? I’ve seen posts about Safari not displaying plugins, has this been solved? Ideally this would need to work in all major browsers (Chrome, IE, Firefox, Safari) on Windows and Mac.

Any help or advice would be much appreciated,