I've seen that the Pilot Rv card is not a credit card in a sense, but a charge card. What does it mean? Can I use it as a regular card?

Yes, the Pilot RV card is not a credit card. It is a charge card, that means that you have to pay off the balance each month anyway. If you don't do it, you'll face high fees and may lose the card. You get a credit limit each month, so you can make purchases for this amount and then pay off. If you are diligent with your payments, then this card is ok for you, but if you are not sure, then there's no reason to get the card. General credit cards for gas purchases will work well for you - if you can't pay off each month, you can do it later and even go without paying any interest. 0% intro APR cards don't have any interest for the length of the intro period, so you only have to pay the minimum payment.