Again, if there's a spell attached to the arrow, the spell might allow SR. Just firing a +3 arrow does NOT potentially fail against SR. Magic weapons work to full effect against SR.
As far as the full attacks...
Actions In Combat :: d20srd.org
"You do not need to specify the targets of your attacks ahead of time. You can see how the earlier attacks turn out before assigning the later ones."
Note, the plural on attacks and targets. You can choose multiple targets, and you can choose them as your attack routine progresses, not when you start (potentially losing attacks devoted to a target you down early).
Your ruling of needing Cleave is a houserule, and if that's how it works in your game, should have been stated at the start of the campaign if possible, and certainly not on the spot like that. Also, your houserule STILL would not apply to ranged attacks (I'm going out on a limb and assuming both questions relate to the arcane archer character), since Cleave can only be used with melee attacks, and thus you would basically be saying ranged attackers are never allowed to multitarget, since you've given them no avenue for doing so. Which is clearly in violation of the expected normality. Look at the
Manyshot feat. Why specify that you can only make the attacks of this feat on a single creature if that's the normal restriction on ranged attacks anyway?
The DM is wrong when he deviates from the written rules after implicitly or explicitly informing the players that they are the rules of his game.
