zencart - 1.3.8

Hi

I have two admin questions.

1.
I see that you are able to increase the order number but not the customer id number as I want to use this as an account number. Would I be able to just change the largest number in the database? will this work or is there another way to add customer account numbers?

2.
Is there an easy method to process customer orders through on the back-end if for example a customer phones up and processes an order over the phone?

Thanks

Jason