They are provided when you purchase the card and vary with the card
No the Credit Card must match the name and address listed for the Playstation Network Account or be a PlayStation Network Card. You can run down to Walmart or some other retail store with the Prepaid Visa and buy the PSN card
Some are available from the Playstation Store
the playstation 3 has the playstation network you can buy games off the playstation store as well as the latest movies, in SD, HD you will need a credit card or a ps3 game card with money on it and bump in the code for some full games, others are free as well as many demos and game updates.
Card numbers are redeem codes and are no longer of value after redemption. I could provide a huge list of ones I have already redeemed, but what could you do with them It's like gift cards before the money is added or after it has been spent
Some you must buy from the Playstation Store
Some are free not all
Some are purchased from the Playstation Store
Some are available as downloads from the Playstation Store. Ebay and Amazon also have some being sold
When you enter the playstation store and look at the products, some of them will be free. Just continue with the downloading process as you would any product.
You can add money to your Playstation Wallet if a Credit Card matching your sign on information is used. You can also add money by purchasing a Playstation Network card at stores and some online sites
Wikianswers will not give username's and passwords.
Some you purchase from the Playstation Store Some are Free at the Store others you earn playing the game