RE: Squat form
Have you taken a look at the videos from Mobility WOD?
Here are a few of the hundreds that Kelly Starrett has done, his pro videos are pay only but he has 400+ free a well:
The Marks Daily Apple link is basically an excerpt from Kelly's book as well as links to more videos.
RE: good mornings
It can as long as you do then in the manner you need to, by this I mean there are many variations on the good morning, wide stance, pulling stance, squat stance, legs straighter, legs bent more, seated good mornings, arched back, neutral back...etc as you can see there are a lot of possibilities. Any way of doing reverse hypers or reverse hyper holds?