Although almost every event in this comic is adapted from existing X-Men stories various details are altered and the chronology shuffled (ie, Xavier is crippled when he first meets Magneto in Israel whereas the original stories had him still mobile; Madrox is on Muir Island more than a decade's worth of stories before his journey there, etc.).
Original story is 40 pages. Probably the first page (which is a splash page with no text of the Watcher in space) has been added.
Original has only 40 pages. Most likely a splash page of Magneto (with no text) has been added.
List of X-Men creators.
Back cover states that the reprint of X-Men #1 is recolored by Piskor but the cover appears to be the original coloring (see the shading on Iceman or the Beast's feet).
Short biography.