The stacking issue sounds like a legitimate bug, or at least something going on behind the scenes preventing it that we just can't see. Either way, pretty annoying.
The issue with the action bars is a valid QoL complaint I think a lot of us have. There are plenty of times, outside of combat, when I want to do things like coordinated buffing or invis before engaging enemies, where the time spent fiddling with scrolling up and down the action bars to find and activate skills on multiple characters becomes a real hassle. This is especially apparent on characters using more than one mage school. I believe having even just a maximum of 3 visible action bars would mitigate a lot of the hassle.
Also, the UI is scalable in Game Options.
