Is there a coffee grinder to grind the coffee beans before you leave the store

Yes, they have. If you cant find it, ask any costco employee, they'll help you.

Yes there is

Yes. They are in the front between the bathrooms and the snack bar. They have two or three commercial-size grinder.

Yes

Yes. It is near the restrooms.

I don't want to bye one I want to use theirs.

No, not that we could see.