Holing along an edge should be useful. Like a subtractive pipe, it should be easy to rule the depth and angle of the hole.
The option could be located after "depth" by ticking and indicate the edge.
Yes, but hole feature can't manage depth hole and depth counterbore/countersink from the edge of the part. It's starting from the sketch.
I've added top clearance in the branch mentioned here: issue #3893