I'm thinking of a small button that could be added perhaps in the middle of the 8 unit slots. The button would lead to a screen like the "Buy production capability"-screen in cities, but the screen wouldn't have anything to do with a city, it would just be an easy way to look things such as plunder, steps, +stack steps etc up. Perhaps the units in the stack could be highlighted in the screen.
It's possible to just unselect stack, find a city that hasn't restricted production and click to the production-screen there for info, but ah, it would indeed be nice with a info-button that's close at hand!
Also found a very minor "odd" thing, not even a bug. When clicking "inspect hero", it's always either the first one or the one on top of the stack, but if a hero is lower in the fight order with a regular unit on top, that hero won't show up, if it's not the earliest hired hero. The risk of something going wrong because of this is small, but I guess it's still there.