Ninja Gaiden 3: Razor's Edge

First 2 bosses in the game are hard as hell, (I figured out a strategy for the robot, pure luck fighting the robe guy) and the game is punishing if you don't learn the nuances of combat. There's no real tutorial, just kind of a "These guys right here are gonna beat your ass, ok? ok."

So basically give me some tips. I have the parry skill unlocked, do I press x or y as soon as they attack or do I let them hit my guard and then press it? How the hell do I kill those stupid guys with the orange light things, they seem to block everything? Also, I'm on chapter 2, I have to hit these guys with my bow while they ride around on these snowmobile looking things, how do I kill them?
---
Apathetic since I don't care when.
i7 3770s @ 3.1ghz, asus gtx 660, gskill ripjaws 8 gb, ASUS|P8B75-V R, ocz 700w psu, 1.5 tb seagate hdd

It's definitely kicking my ass. I'm thinking maybe I shouldn't have jumped right into normal mode because even that seems too much. I don't think the original game was this hard on normal but maybe I'm out of practice. Can anyone confirm?