Well yeah, basically i completed the game once and have now started a second playthrough on a different difficulty.

so how do i carry over all the info?? i know its possible because ive seen loads of videos of people who have loads of advanced stuff on stage 1.

does the new save have to have overwritten the old save?

thanks

oh ok...thanks you guys alot.

Just load the old save, and it will ask you what difficulty you want for your next play through.

Well, of course you have to load your completed save game and choose a difficulty.
(Doesn't matter which one..just don't go too hard =P)

And when you arrive at the part where you meet up with the MKII, you get all the stuff you had in your previous game.

load the previous saved games like the previous mgs titles did it