Also with pay-pal I need to make an account to use it.
Nope, you don't need to make an account. Just click on the "Pay as a guest" link and you'll get a check-out form just like any other online purchase. It tells you this on the membership page too.
Further I only see creditcard number and other codes specially for the credit card, where is the option for a debitcard?!
Paying with a debit card should be no different than paying with a credit card. Just type in the numbers on the "Debit or credit card" tab.
Is it possible to hide those advertisements with a membership? I saw a thread where a member still had those advertisements.
Yep, members can play completely ad-free. Or they can keep the ads on -- they have the choice.