Ruling on depositing money in the bank, and interest

Borrowing from a riba-based bank in order to buy a house

He used a credit card, which is haraam, and he owes money. Should he pay it off?

Is it permissible to act as guarantor for a person taking a loan from the bank?

Does paying more than the amount required for zakaah mean that one is allowed to take interest?

He bought a car by installments from the bank, then he sold it so that he could use the money to get married

What should be done with interest?

Can he accept money that comes from the lottery company?

How could the Islamic states allow the development of riba-based banks?

Saving system in Aramco and attitude towards the various fatwas concerning it