Hi Brenden,
unfortunatly you can't edit the template for the column width's however when you do an invoice it should display the terms in the top right hand corner
something like this.
Tax Invoice
Invoice Number 111
Issue date: 7/2/2010
Due Date: 12/2/2010
Sales Person: Graham
I have had so many complaints from my clients as they miss the terms at first glance and have asked if it could just say
terms: 30days
or something similar
As for your payment options what I do is open the options, click on Invoice and in the Note Comment box I add them in there and when you print the invoice they are at the bottom.
With the discounts you could do a few things
1. put a -value as a line item
eg: -$50.00
2. you can turn on the discounts column in the options under the other tab. However this will only allow percentage discounts not dollar discounts
Graham