Need 2 Pie Register Wordpress Plugin Conditionals Added

I've added the Pie Register Wordpress plugin to a website and need two conditionals added. Pie Register has a provision to allow you to charge a subscription for people registering on your website. This seems to interface ok with Paypal, however I've set up two registered user types, "Buyer" and "Seller". I need the ability to only charge the Seller a subscription fee, and not the Buyers. The Buyers need to be able to register for free. As this plugin sits, the Paypal button is shown to both the Buyer and the Seller. It would seem that a conditional statement should be able to handle this by not showing the Paypal button when a Buyer registers. The website currently only allows register users to make comments on any posts. I'd like to restrict commenting to only the "Sellers". Those are the two items on my wish list. I can provide a great deal more detail if needed. This should give you the basic idea.