Automatic Shop Order generate.

Hello,
I have a couple of questions regarding the auto generation of shop orders
from sales order entry. 
Our company has just turned this feature on, and we are having some issues
with the process.

First, it seems as though a shop order generates even if you have sufficient
inventory for an item. Is there a way to tell the system to only generate a
shop order if you do not have enough material to ship?

Next, we require that a retainer sample for each blend produced to be kept
in the lab. Therefore, we must create an additional .06 lb for the retainer.
Is there a way to have BPCS add this quantity to the amount of the shop
order being generated?

Next, we would prefer to have the lot# pre-assigned on our shop orders.
Currently, we are revising the shop order and changing the flag to
pre-assign before releasing the computer generated shop order. Is there a
setup parameter to change which will automatically set the pre-assign lot
number flag to yes?

Thank you for your help.
Ted