The focus-point issue depends on your personal habits. Many people who shoot a variety of non-action photography, only ever use one focus point. Yes, one focus point, not one cross-type, one focus point in total. You do that using the focus-lock and recompose technique.
On the other hand, having multiple focus points and particularly more sensitive ones is very beneficial when using continuous or tracking autofocus. You say that sports is not what you will be shooting, so I'd consider it less important.
The most significant difference feature between these cameras is that the 5D Mark III has a 100% coverage viewfinder. If you want to frame precisely and not have to crop all your images afterwards, this is essential and neither the 6D or 5D Mark II offers this.
The flash-sync issue is probably a non-issue if you are not aware of it :) What it means is the the 5D Mark III can use flash with a higher shutter-speed which is needed to augment the relative flash contribution when shooting in bright light.