I agree that would be great!    
 
I would advise against putting everyone under the same Customer ID or Code.  
 
We used to do it the same way.  But with xcharge credit card processing, it might take a couple more strokes, but having an account for every customer is the only way to go.  
 
If you have a repeat order.. Everything is already there! And having the email address in the system allows you to market directly or contact the customer in the future.
 
For all of our Credit Card or Cash customers we use a code similar to MOKRIE$   Where the first two letters are the state name, the next four or five letters are the customer name and $ for cash/credit card.  The "$" tells us that the customer does NOT have terms with us.