[all variants] Spice questions - does anybody have experience with it?

I've never tried Spice, but would like to give it a run. So here some noob questions:

1. Is Spice able to use the graphics card to render the picture/video?

2. How well does Spice work when running a game on a remote desktop over LAN?

3. How good is Spice on Windows 7?

4. How well does it perform in a Linux (Ubuntu) VM?

5. Is Spice already supported under Xen?

Thanks in advance for your answers!