Credit cards

Q: My question is that I live in muscat and I am a teacher. I want to start a side business. So the bank is offering me a credit card and the offer is that if I pay the money back I use from credit card in 52 days then no interest will be charged. But I will only use it for the business so please tell me what Islam says about this? Will look forward to your reply in the lights of Islam.

Q: Is it permissible to use credit cards as long as I pay off the balance without having to pay interest?

Q: Is it permissible to use a credit card if one ensures that the balance is always positive and never goes into credit? Also, interest is paid to the cardholder because the account has money in it, but every month the amount is reversed when requested.