yes ,you have to have it or credit card. The Credit card is better because network cards are only sold in denominations but work well when you can not use a credit card
PSN is free the cards are for DLC such as games or addons Live is the name if the Xbox internet service, Playstation is the PSN or Playstation Network and it does not have a charge to sign up. Network Cards are never needed except for purchases you want to make. Even then they are not needed, you can just use a credit card to put Money in your Playstation Wallet
No, to redeem the Japanese PSN card you need to be signed into the Japanese PSN.
You need an internet connection and a Playstation Network Account if you mean the Playstation Store
After you have downloaded them no, unless they are online games .
a router or a modem
After you PS3 has an internet connection you need to register and join the Playstation network
Yes all you need is a psp
No they are downloads that must be done with Playstation Home but not for just to get to the Playstation Network. There is of course space taken up in you PS3 harddrive as files are created including the account information. There could be what is called a download each time you get information like your trophies status, but you do not download the Playstation Network and instead download the information needed.
Yes. PlayStation Network allows you to save your billing info (ie. a credit card) to your account, allowing you to buy games on the PlayStation Store on the PlayStation 3 and PlayStation Vita without the need for a prepaid card.
No because you need a router to connect to the playstation network
Yes, you need a PlayStation Network account so you can go to the PlayStation Store and download it. The download is free, and a PlayStation Network account is free. You will not even need to input a credit card number.
No PS3 does not have Live they have the free Playstation Network and for the cost of Live you can purchase Playstation Plus that provides members with free games and reduced download prices. You do not need to join Playstation Plus to play on the internet or use any of the Playstation Network features