Q 1 : I have already sent an invoice to the customer but I forgot to include the freight charges. Is there a way to enter a freight only invoice? 

A 1 : Yes there is. For you to be able to make a freight only invoice, you must have an invoice model where the packing list requirement is relaxed. To do this, you have to go (F8) Options menu then choose Auxiliary Utilities. In option # 35 under Auxiliary Utilities, you can create an invoice model called Freight or any invoice model name you want. Then go ahead and add a new invoice under that model and do not select a packing list. Enter the freight amount on the invoice add screen, and then when prompted to select an inventory item, press ESC. MOD2 will ask you if you are entering a freight only invoice. Confirm by typing "YES" and finish adding the invoice.