Hmm, he's far too old, only CSM can reach live for millennia without being stuck in a dreadnought. The introduction i think is a bit useless. You just list up a bunch of things he's done to become who he is today, which does not work well for stories. Instead of doing it like that, either leave it out, write it in less chunky form or use it as memories. It's all a bit over the top too, with holding the Chaos Lord in the sky and the hordes of daemons. Space Marines are uberhumans, but reading this i get the feeling they're all from Krypton. I also don't think someone would refer to his own weapon as a "plasma/bolter combi-weapon", more likely a bolter with underslung plasmagun or something like that.

Still, it's entertaining, don't let us get you down.