So can sentence no. 1 "What interest rate does this account offer?" become "What's the interest rate for this account? or sentence no. 2 "What's the interest rate for the savings account?" become "What interest rate does the savings account offer?"
Welcome to the forum, Venco. As POB says, all four sentences in post #3 mean the same thing. They're all interchangeable; it doesn't matter which one you use. (In English, there are often several perfectly good ways to say the same thing, not just one.)