Your age updates itself automatically, hopefully you put the right birth date in.
No, this is not possible
No, PSN is free and there is no indication that is going to change.
Well you can not change your age because your age does not change. You could open a new account, but if you are under 18 you would still need someone to have the master account an address and a email address
You can not change your name and can only add a new name or start a new account
No, you must be at least 13 to use a PSN account. Even then you need to be 18 to create one. Playing on a PSN account under the age of 13 can result in getting banned from PSN.
You can play some games at any age
You can only add a new name
You can't but you can always make a new account
You can only do it on a japenese account, go on youtube and it will show you.
The related question lists the reasons that you can be banned
You should be able to change it at your house, if you can't get it, you should contact PSN and say your purchase didn't go through
If you change your password to your PSN account no one else should be able to log into your account on any PS3. You can not remove data from another Playstation 3
no you would'nt be able to go into psn network.