Construction menu for frigate based armies

So I watched a few games of 2v1 (standard AI vs standard AI with me observing in the corner) to try to figure out how the heck the AI is so aggressive in the beginning, and I learned a ton about their opening moves.  I also learned that the AI creates armies with a single unit (something I cannot seem to do as a player, I need to have at least two units to create an army) and that they also can use the 'request reinforcements' feature with that singular unit without having to first build a cruiser class unit.

My question is, why is it different for the AI and the player?  Why can't we create a single unit and have an "archer" be the leader of that army?  Probably the single best feature to this game (IMHO) is the army feature and the request reinforcements ability.  I do hate how if the leader of the army is 'ugpraded' to a stronger unit that the control group disappears, but that isn't that hard to adjust to (though annoying).  

One last side though, I would really appreciate a 'split army' button.  Cut the army in half as best as it can be.  Sometimes you want to combine everything for a big fight and then need to spread out afterward to conquer in multiple directions, and the current controls in the game make it *incredibly* annoying to try to pull out just a few units from a large army.  Somehow a unit can be in two different control groups at the same time, even though he may be in an army in one control group.  So you end up really mucking up your armies when you try to split them out.

Anyway, that's my 2c so far.