you could have a huge problem with card charge backs. Lets say somebody stoles a creditcard and buys BTC. once you will get under investigation you will have to pay back the funds you got from the card plus your BTC is gone.
That's a universal issue. You can avoid this by adding some barriers like ID card verification. What do you think of the model.
No you can't.
Assuming you have a user ID or whatever, you do not have any right to use it in case of a credit card charge dispute.
Even if you do, you will lose the dispute.