The behavior is, currently, a lack of an xorg.conf attempts to FORCE avwiz to run, to create one. At worst, you should get a "failed to setup X" window, which we could begin to troubleshoot. The idea that an xorg.conf is needed to GET to avwiz is counterintuitive.
The fglrx driver we use is the fglrx in the repo and for an HD6xxx series card should absolutely work. In fact, moving to the newer fglrx drivers in the repo will only drop support for the HD2xxx - HD4xxx series, while adding support for some of the newest chipsets. In general this is not recommended to overlay on our system without making certain changes. What usually ends up happening is that you get a blended version of the driver because our detection scheme will absolutely insist on the .deb package being installed... which is what has happened. Most likely the config from the newer version is what fixed the modeset, which is what is almost certainly at fault for the blinking screen.
Anyway... glad you are up and running. In the future, please come find me in IRC so that I can troubleshoot this so that it works out of the box for everyone. Downloading the eternally support dropping newest version from ATI is not an option.
There are a couple of issues I have personally noticed and made tickets to try and fix as well. The first boot of ANY Intel, under any circumstance, locks up. Reboot solves. I have no idea why. Also, depending on selected resolution the entire UI is shifted a few pixels up. This baffles me as well. Please confirm or deny those two behaviors.