Downloading apps

You need a verified payment method, unless you created your Apple ID without one.

Once the payment method has been verified successfully it can be removed, by setting it to "none" and it will not ask for a payment method again unless you incur in a charge that cannot be paid for any reason.

See here: If you can't remove your last payment method or use no payment method with your Apple ID - Apple Support

Perhaps. It depends on your specific situation. Whatever information you do have on file must be current, accurate and complete. The information may be used to verify your identity.