I'm not talking about formulas, I just know from experience with different troop counts and with or without crates and quickmarching myself. I think your scout would learn these things from experience too and not pull out an abacus in the field.

The hardcore will always be there calculating this and that and min/maxing to precision.
I do agree that a direction arrow would be a nice addition and it would go away when you are not moving to leave a little room for posturing and keeping other armies guessing about your intentions. Great idea. We may need to have the ability to zoom in closer to see the arrows when it gets crowded, however. I think we could use more zoom levels even if we don't have direction indicators. I've seen some confusing clusters on the map on occasion.