Yeah, it's safe. The reason it is safe is that the only way Apple could charge your card would be under their name, and they can't do that because then the world would stop trusting them. If they somehow did it under a different name, the police would ask them where they gave out their credit card and the most commonly said thing would be an iTunes account. Making a different name for each credit card would be far too difficult, so, with Apple, you are safe. You don't need to use a credit card if you don't intend on buying anything. It is called making an "app store" account. In order to make an app store account, you need to go into iTunes and attempt to download a free app. It will tell you to make an account, so do it as you normally would. Under payment options there will be a new option "none" and select that. There, no credit card required.