Hello Jessicawade,
I noticed that you updated this question. The answer below still applies, but I can add a more recent WordPress plugin solution that will meet your needs: Sprout Invoicing. Sprout is a great invoicing solution and it's easy to customize.
I checked to see if they had anything detailing payments with PayPal Pro and I found this link.
Hope that helps!
Arnel
I don't have a specific solution to recommend (all of the ones I've worked with have been high-end and custom), but I would advise you to consider whether the iPad is truly a convenience or just a coolness factor. I've seen companies deploy ERP with iPads and not once have the iPads been used as intended - the staff has discovered that it's much easier and faster to enter data on a computer and only use the iPads for email and personal use, making it an expensive experiment for the companies involved.
I don't have a specific solution to recommend (all of the ones I've worked with have been high-end and custom), but I would advise you to consider whether the iPad is truly a convenience or just a coolness factor. I've seen companies deploy ERP with iPads and not once have the iPads been used as intended - the staff has discovered that it's much easier and faster to enter data on a computer and only use the iPads for email and personal use, making it an expensive experiment for the companies involved.
Thanks for sharing your experience jessicawade.