Yes Google allow different accounts with same credit card - a lot of people do it (under a same MCC account). They don't allow promoting the same business/keywords with multiple accounts.
yahoo allows you to use the same credit card/paypal account on different accounts but I never knew google did
Yes you can, But you CANNOT run the same campings (same keywords or similar ads) from different accounts. They will see this as you are trying to manipulate their system (like getting several of your ads display for the same keyword). Tim