I want to start a contest on one of my web sites where the site/person who brings in the most visitors to a certain page on one of my sites each month or a defined period, wins a domain name(s) of their choosing. It's targetted to those sites on free hosts etc without a domain already or if they want another one without paying.

My dilemma is if most of the target people don't have a credit card. So if i register say a 2yr domain from 000domains.com and transfer the domain to the winner and he doesn't have a credit card for renewal. Does this mean the domain will expire after 2 yrs ?

When you transfer a domain to a new owner, does the new owner need a credit card on file ?

No, the new owner, or the one who is registering the domain name, does not need a credit card at all. He can pay by deman draft, or cheque, or whatever other way he wonts.