If I understand you right, to get started to make all the pages that I need, I run Checkout Wizard and choose, say, PayPal. When I get all the pages, I change some parts of the generated pages depending on the my Gateways documentation.
The payment method I am going to use is called Hosted method.
My question to you is then which pages and which parts of the pages are to be changed?
The link to my gateway has the following info.