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W9 is request for identification number. It is used by other organization to request identification number from you. Who are you requesting identification number from and for what reason?
Having social security number doesn't necessary makes a resident. If you are US citizen or green card holder, than yes, you will file your federal return as resident, but if you don't live in CA and have no intention to return to CA, you are CA nonresident unless you choose to do so (but I would not recommend it).