Setting Up Paypal Website Payments Pro Payment Gateway

Hello,

My customer is using Paypal Standard and the setup was straightforward and easy.

Now we are looking at using Paypal Website Payments Pro Payment Gateway because we want to accept paid Events Bookings.

My two questions:

1. The instructions to set up the Paypal Payment Gateway look straightforward. After I upgrade my Paypal account, I add the Username, Password, API Signature into my Business Catalyst website. Is that it? Will our shopping cart will continue to function like it has? Or are things more complicated than that? Or will I have to make other changes for the shopping cart system to work?
2. There is mention of setting up Cardinal Centinel. (We are not using recurring billing). I'm not really sure what the Cardinal Centinel is all about. Is that an important part of the setup of Paypal's Payment Gateway?

I'd like to be prepared before I start down this path.

Any advice would be appreciated.

Thank you,

Tricia