Yes it was announced as the new MGS Game MGS:R its believed that Raiden will be the main character
Raiden is actually from MGS2. But, Ivan Raidonovitch Raikov do looks surprisingly similar to Raiden.
Oh yea. It's all about using the Missiles that lock onto machines only. Load up the deck with MANY of them.
You get to make it up.
Raidens age is unknown
Konami has said that in an upcoming expansion pack to Metal Gear Online you will be able to play as Raiden