Thanks a lot Pocus, I didn't know about the space bar, I guess I will have to try. As if this complain was only due to my silliness, I remove this grief.
(Don't ask me how I didn't spot this feature, but that seems to be usual as I also overlook the Combat Replay for two months in SE:IV)
You could manage a thousand units with a few tricks, but tactical combat would be 1) Time-consumming to develop 2) Time-consumming to use, especially if you spend a lot of time to give orders to your units.
PvK, I spoke about the inability to target specific units with spells only. I do know you can order your other units to do almost all you want, and this system is much better than in SE:IV, which in turn is so much better than AOW with regards to auto-battle. As I wrote earlier, the problem with being able to aim the spells at a specific kind of units is linked to balance and fun, as it used (or would have? I am not sure if that feature was in the game at some point) to make most battles into a duel of battery fire of spellcasters.
Finally, for the trouble with archers, don't shields help against arrows? I seem to recall this was working fine with me. Of course, spells are much more dangerous, but maybe that's because Arcana cannot be controlled by mere human beings.