Deposit on a Sales Order

Deposit on a Sales Order

Good day,

100% of my business is preorders, no inventory. I am trying to run away from QB for one of my businesses, but I require two options that I don't seem to find with Zoho Books. 

1 - If there is a way to apply a deposit on a sales order, as with QuickBooks (yes, unfortunately, I also use QB for this same reason)
2 - Since I do not keep any inventory, all my business is special orders and consulting. Is there a way to create a non-inventory item? For consulting i use a service item. 

Please do not suggest an invoice. If I do an invoice, I have to pay business tax and GST on the full amount, even though the invoice is not paid. 

The intent is to send a report to the customer showing their balance for each order. 
Thanks
Rudy