In response to your first question I am assuming the nose shae and mike are switching gaps . Most teams run a gap control defense and when they stunt they still leave every gap covered so if the nose shade stunts to playside a gap the mike backer would no longer be responsible for playside a gap but would then move to backside a gap.
You do have a point, will could come and take backside a gap and the 5 tech could slant to backside B, that would leave a safety responsible for contain and wouldn't be a great Defensive move due to the bootleg and end around.
We do similar ace, duece and trey calls. However we do not look at these as zone blocks. When we run iso, power, counter, etc we use these calls, when we run a "zone rt or lt" we try to block it just like zone block for pass, with us attacking the D.
In this example I am trying to think of the D logic and gap control. i was assuming when the D line stunts strong the backers would have to take over the gaps for the d line. And the d would still have to think of contain on the QB.