For both of your product, where you want to collect information, you will want to use our Variants and Variables features. These features, combined, allow you to collect up to 6 pieces of data, three of which can be manually typed in by the buyer. Here is link to our help page on our variant and variables feature:
http://www.e-junkie.com/ej/help.variants.htm
Integrating with PayPal is simple, all you need to do on E-junkie's side is, after you have an account, go to Seller Admin>Edit Profile. On the right side you will have a field to type in your PayPal account e-mail address. Then click Submit, this will take you back to the seller Admin page. Now click on the option Edit Payment Preferences, also on the right side. Here you will want to verify that there is a check mark in the box for PayPal Standard. And then once again click Submit.
There is not set subscription plan you will need for either of the above. You will need to get a subscription plan that gives you enough room for the number of products you want to sell and room for any digital downloads you plan to have available for purchase, this would not include images or data you e-mail to your buyers after they pay and send you the data you mentioned needing for your products. Here is a link to our pricing page:
http://www.e-junkie.com/ej/pricing.htm
As for integrating with Wufoo. If you are able to collect the data you need with our options you may not need to worry about setting up to use Wufoo to collect data from your buyers, depending on your needs. If you do need to use Wufoo, then you will need to add the page with their form/survey either before the buyer will click on the E-junkie cart button or after. If you place form/survey before the payment page, and it creates a user ID or any unique ID, then that can be added to your order data, through our button customization so you have a number to connect the information at Wufoo with the information in your E-junkie account. Here is a link to our button customization help page:
http://www.e-junkie.com/ej/help.custom.purchase-buttons.htm