Penalties are just god awful in this game

First clip I don't think should be called a penalty.  There is a lot of LT going on there and that effectively makes it so you are turning your back to the hit.  In the actual NHL rules hits from behind incorporate if the player put himself in a position just like you are seeing in this clip.

Second clip its interference because the puck battle has already occurred between the attacker and a different defender.  Puck came loose and the second defender came in to level a hit.  To me that looks like a good call.

Third clip I absolutely agree with you.  Board battle, no last minute adjustments.  Second defender in just rails from behind, that should have been a penalty.