How to show line numbers on invoices and quotes as well as item headers

Hi, good day. (Please refer to image below as example from excel)

1. Is there a way to number the individual lines on quotes and invoices? Sometimes we want the clients to reference the line numbers on their quotes.

2. Is there a way to segregate the groups of items on a quote/invoice with headers. These headers depend on the service we are rendering. I already tried to use a dummy inventory item with no price for this, but when we preview, the quantity for the line is shown as 1 and the price is also displayed on the line. Maybe if there was a way to only show the quantity and the price only when it has values greater than 1 would be helpful. (example in excel in image below)