Ok, so I have some siege combat coming up and have been looking over the siege engine rules. I understand how it works with aiming-reloading on full-round/move actions. Where I am at a lost is what is the action to fire a siege engine? Is it just part of the Aiming and not an action? I've read through the rules twice and done some google fu and can't find an answer to this. Thanks.
Is a normal attack action = standard action to fire a siege engine. You cannot perform a full attack because you need some actions to reload the weapon.
A light balista can fire every three rounds (2 full round actions to load, one standard to fire).
With the master siege engineer feat you can fire every 1.5 rounds (2 move actions to load, one standard to fire).
Can you man more members on a crew than what's listed in the entry? Could you put an extra man with you on the light ballistic to load it for you so you can fire it in the same round?
Well, according to the table, you still can't get iterative attacks with a siege weapon, even the light ballista. That said, if you had Quickdraw, and the ballistae were next to each other, by RAW, you could...
Sorry, I choked trying to chew on that much cheese.