[Suicide Junkie]

...a floating window which would appear alongside a selected unit which would only contain applicable buttons (reducing wasted space)
Do you know about the right click order menu? Select a unit, then right click (on the destination in case of remote actions) and select from the menu.

Also, try turning off the alpha sort (and use KwokStock if you aren't already). Instead of "Ion engines" being completely separate from "Quantum", things will look much more like a hardware catalog, and you won't even need the filters.