This post contains all of the information related to learning the game. If you have any questions you can either ask me on twitter by tweeting @Jukspa(faster) or just posting here.
The fastest versions are 1.1 and 1.0, as far as I know there's no notable differences for speedrunning but I've always used 1.1. You can get them by either getting a physical copy or by pirating. The steam version is slower as you cannot gain height while circle jumping.
Segmented run of crysis in 42:10(without segmenting penalties):
I learned the run using this as a basis but it's now outdated because of route improvements.
There's one currently useless trick that isn't on the SDA page or any of the tutorials, which is clipping with props. You can just throw stuff at your feet while being next to a wall which can cause you to clip through a wall, but as already stated it's not useful anywhere as of yet.