No the games and PS4 system have not yet been released and there is nowhere to play them unless you are part of the EA family of developers with an advanced release PS4 for the game developers
No you will not be able to play the games either way. Systems changes on the PS4 allow them more design capability for games and many titles will be released in a downgraded PS3 version. You still will have to have a PS4 to play PS4 games and a PS3 to play PS3 games.
Yes, you must buy a PSPlus membership to play online games on the PS4.
No, the PS4 will only run the games made for the system. But there is a application on PS4 called PlayStation Now which will allow you to play PS3/PS2 games for a price.
No it will not
No, the PS4 does not have backward capability and cannot activate (play) PS3 or PS2 games.
In short, no. Sony haven't released any information regarding a PS4 yet, so we can only assume that you cannot. It is highly likely you will be able to play PS3 games on it, that is - if it really comes out.
No
Not without emulation.
No. It is not possible for a PS3 version of a game that is also offered as a PS4 game title to play against each other. They can not play because the games are different software and whether they are both on the Playstation Network does not matter because the games are not compatible
No and neither console plays the others games
approx. 65 million
There is no age requirements for EA Sports games, but just look at the ratings to make sure. I know for certain that you must be 13 to make an account for EA Sports.