font face="font face" what font faces/styles are supported?
font size="##" what sizes are supported?
font color="color" what colors are supported?
As far as I know, there is no choice for any of this. You can do bold, and that's about it now. There used to be more options, but I think Amazon would rather stuff look more uniform.
Where can I upload and see how it will look on Amazon before I upload my product descriptions?
As notjohn said, once the book is live you can do stuff through Author Central (though still nothing fancy), but anything you change on the upload pages will knock it back to whatever you first put in the description box. You can go back and fix it again, but what a pain.