Bumblebee and AMD Radeon cards

The official AMD fglrx driver has some support for hybrid graphics itself; there's less need for Bumblebee and solutions like that.

Of course, this doesn't work on the AMD/Intel hybrid system I have, so I'm not sure quite how good the support is. ☺

As you can see from the very first stuff you read from the Site.

[...]nVidia Optimus support for Linux[...]

Bumblebee aims to provide support for nVidia Optimus laptops for GNU/Linux distributions. Using Bumblebee, you can use your nVidia card for rendering graphics which will be displayed using the Intel card.

So no, it's for Optimus enabled laptops Only.

Currently, Bumblebee supports NVIDIA hardware only, but the Bumblebee Project team is investigating options for AMD Switchable Graphics Technology which can be tracked in issue 52 on Bumblebee-Project/Bumblebee.

As far as I know, the fglrx driver already supports hybrid graphics as was mentioned in http://forums.gentoo.org/viewtopic-t-909802.html. The radeon driver does not have this option, but may be supported by Bumblebee in the future.

As for your second question, commands must be preceeded with optirun only if you want to run it with the discrete video card, e.g. optirun firefox. It will obviously not work until support for AMD hardware is implemented in Bumblebee.