2.) Have you missed that 1/8000 shutter speed ?
i don't believe 1/8000 will be missed by many, or if the exclusion will even be noticed.
just out of curiousity, i did a metadata search through my archives and found a handful shots at 1/8000 - images shot at 1.2 or 1.4 in broad daylight for DOF, when i really should have been using an ND filter
I don't think you going to miss the 1/8000.. the 6D you can shoot at 50 ISO... (50~4000 or 100~8000, is almost the same)
IMO, the 6D has the best AF from any camera from Canon to date, the camera can focus DEAD ON using the center point which I use 99.99% of the time, and I don't shoot moving subjects, like sports or anything similar...
Buying this lightweight and solid camera, best AF center point, and the best ISO performance from any Canon camera?.. its a winner for sure.. that's why I bought 3..