Yes, you have to pay for TurboTax first before you can set up direct deposit. Once you click the "File" button you will see three steps. The steps must be done in order.
In Step 1, you pay for TurboTax.
In Step 2, you enter your direct deposit information.
Yes, you can pay with your debit card as long as your debit card has a Visa, MasterCard, American Express, or Discover logo on the card.