Xbox One X vs. Xbox One: Game Redemption and Compatibility Inquiry

Hello everyone,

I own an Xbox One X. The other day, my cousin sent me a Game Pass code to use. When attempting to redeem it on both Xbox and Microsoft platforms, I encountered a request for my credit card information to proceed. Living in Tunisia without access to an international credit card, I found it challenging to proceed with the redemption online. Given this situation and my subsequent confirmation, my question is: Is a credit card also necessary to redeem an Xbox gift card?

Additionally, I have another question as a new Xbox user. I'm curious to know if Xbox One X is different from Xbox One. Can I play games on Xbox One, or do I need to purchase games specifically for Xbox One X?

Thank you.

:)