Will this affect my credit score?

I have several questions.

1. I've never had a credit card, but I do have a checking account in my name. Do i have a credit score?

2. I've applied for "Bill me Later" on paypal about 6 or 7 times the past year and have always been denied.

3. Does applying and getting denied for different credit lines affect my credit score? (providing I do have one)

4. My parents don't want me applying for a credit card because they want me to co sign in the future when they buy a house. How can I possibly co sign for a mortgage without a credit score?

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