Nice purchase David! Just wonder if there were any reason you went for the kit with the 24-105 STM lens and not the 24-105L USM one, other than the price difference? I have been looking at this camera as well, and I will probably buy one when I go to Japan in a few weeks. But haven't decided which kit lens to choose.
As for flash, I have the 580 EX II. Can highly recommend that one.
With my old Canon camera, having the flash turned on, but without actually using flash, had a create impact on the auto focus. Maybe for a better camera like the 6D it might be less noticeable.
