5)This whole thing just seems like you aren't used to this style of clearing content.
After establishing hate (1-2 flashes) you are actually generally safe to 1-2-3 a large, hard-hitting enemy in the pack because the mobs will be stunned for 5.5 seconds, just enough time for you to flash back or Cover anybody who's riding your threat. This is the sort of thing a good tank will do that does not need to be done when you are single-pulling. It should not be surprising that players need to be better when you are doing large pulls.