I usually don't bother with SSL unless I'm doing any form of eCommerce or if the data being passed either way is sensitive in any way. This might mean the data is protected because of its business application, or perhaps someone's personal data.
A MasterCard is a type of credit card used to make payments electronically (eCommerce). There are many other types of electronic payments such as Paypal, Visa, DinersClub, etc. I'm not sure I understand your question.