1) If an ally is subject to a hazard attack at the end of their turn and Legacy chooses to intercept, is he also subject to an additional hazard attack for moving into a hazard space?
2) If yes, then if Legacy was also originally in a hazard space, would that also make the ally subject to hazard attacks for moving into Legacy's old hazard space, AND for still being the end of their turn?
Yes to both. Legacy and the target can continue to swap spaces until you let them face attack.
By the way this is a great way to use Baron + Legacy.
Example: I run Legacy into Ra's Living Pyre to Punch Ra, then Baron with Sabre and Redistributor gets himself attacked, swaps with Legacy and uses redistributor to hit Ra with his own Hazard while Legacy faces Baron's attack.