I would recommend looking at some of the documentation here before getting started:
The process of setting paypal payment pro should be similar to setting your paypal payment standard. However there are three required API parameters (signature, user name and password) which you will need to get from Paypal.
you don't have to have a ssl certificate, but if you are running a site does transaction it is highly recommended.
When you setup paypal payment pro, you can charge customers with our having them to leave your site. when you run the check out wizard a check out form page is created which allows for customers to enter their information.
Let me know if you have any additional questions.