All I know atm is that it enables you to make better things, Idk about success chance though... i wish they would release EXACTLY what each skill does...
As for high end player crafted armors being useless, not to laugh but.. HAHAHA... The only way to get these armors are from them droping DIRECTLY from a mob, or to craft them from manuels that drop from mobs... You can't buy armor higher than level 33 from NPCs...
Armor-crafters and Weapon-crafters can make some cash for thier troubles, though alchemy is lacking ATM... but its no easy thing...
~Mikalo