my only advice is that you should place your cannon right in the middle of the battle line protected by pikemen. this will draw the enemy to attack your center to take out the cannon.

arquebusiers like most missile units should be places on the left and right front of the formation to cover against horse archers or shoot into the expected central attack from the flank.

once the battle closes i may withdraw my artillery units completely from the battle depending on the circumstances or have them leave their artillery and regroup behind the main body in case they might have to be used as a last ditch reserve.

one thing i have learned from the game mechanics is that if you back up zwehanders or other infantry with pikes when a powerful enemy charges the pikemen suffer the effects of the charge even though they are behind. i would use the pikemen forward and when the battle joins you can use your melee infantry to either march through the pikemen to take over the battle or swing them around the flanks.