Wufoo and URL Modification

I am trying to use Wufoo to do process payments for my website. My company offers a service and Wufoo allows me to gather the data I need as well as collect files from the customer along the way to figure out how much they will be charged, and then it charges them directly.

The problem I am running into is Wufoo doesn’t collect the data from a logged in user such as name and address. However, they have a function called URL Modification:

https://username.wufoo.com/forms/form-name/def/field5=wufoo&field6=today
The above URL would place “wufoo” in field5 and “today” in field6 when the form loads up. Remember to reference your account API section for the Id of fields on your form. The end of the URL can carry on forever as long as it follows the fieldX=value&fieldY=value2 format. Each field is separated by an “&” character.

I would like to see if there is a way when a user clicks on a link it grabs there user information and inserts it into the URL so that my customer doesn’t need to keep re-entering their information.

As a side note, the reason I am looking at using Wufoo instead of Ninja Forms, Formidable, Form Maker etc, is because those don’t support payments. (Formidable does, but only paypal.)