I often use a mounted archer sovereign, and those animations can take surprisingly long times to finish displaying; i end up right clicking the next target repeatedly while waiting for the attack animation to finish; it seems like it pauses a bit after finishing as well. It may take as much as 10 seconds; it seems like it waits until the mount is in a particular position before firing. (Which is probably because in the earlier version the mount would snap to a particular position when attacking, which looked bad.).
The game also seems to bug a bit with the occassional counterattack; enough so that you can't give further commands. The only way out of that I've found is with auto-resolve. I got that in a fight for the legendary armor of azure (sp?), I auto-resolved and won, which bugged the mission. (I didn't get the armor, the quest is still there, but nothing happened when I went to the quest location).
I guess what I'm saying is, some more work is needed here, unfortunately I can't be more specific. Sometimes the game does switch to quick move-ish mode, but I see no rhyme or reason to that either; it's not something I make it do on purpose.
For the 'next unit' key, though, use 'pass' (space bar) to switch to the next unit in tactical combat. It doesn't work in global, though, and you end that unit's turn, but still.