When I looked into getting a home gym, I looked into and read more about smith machines at which point I decided they were a bad idea. Smith machines only allow you to move along one plane of access which can cause injury. Also they don't allow you to use supporting stabilization muscles.
I know there have been some new smith machines that allow you to work on 2 axises which helps some but generally something that allows you to move freely, such as using a cage, is probably the best bet.
You can't out-exercise poor eating habits.
Very interesting. I had been guilty of the too deep leg press issue, and now that I've stopped, my knees no longer hurt. Imagine that!
As for slide #13, people reading on the cardio machines drive me crazy! I'm working so hard I can barely breath and you're thinking this is a library? Three words for those folks: Audiobooks or Podcasts!