Friendly Fire:

If you leave your archers on Fire At Will, and do NOT tell them to shoot at anyone in particular, they will pick and choose their own targets, and they will stop firing at an enemy unit if your own men engage that unit. This is best when you leave your archers up on a hill to harass the approaching enemy. When your flankers engage, your archers will look for new targets. This helps cut down on (but not prevent!) friendly casualties.

If you tell your archers to fire at a specific enemy unit, they will continue firing at them even if your men move to engage. This is best when you send a unit of ashigaru to slow down the attacking monks, and you have your archers pepper the melee indiscriminantly. In this case, we don't care about our own casualties, we just want to kill monks before they reach us!

Unit Stats:
I think it does still track the soldiers individually. If you have the newest patch, check out the info in the Log File. The numbers is shows on the icons is just the avaerage for that unit.

-- B)