we'd decided to create our own paypal link in the invoice that we're sending. 1 question and 1 problem.

first, the problem:

when editing the invoice notification email is supposed to be like this.

https://www.paypal.com/xclick/business=email@address.com&item_name=%CustomerName%&

item_number=%InvoiceNumber%&amount=%Total%&currency_code=USD

but everytime when I'd saved the template, the last holder that is the currency code will be changed to "¤cy_code=USD" instead of "&currency_code=USD"

secondly, the question:

my client should be able to pay an upfront of 60% for their first payment. any way that I could let the system generate that amount from the total amount?