Agree and disagree.
1) Everyone does have to do squats. You don't have to do anything you don't want to do, I agree. And yes, people with back issues should either not do them or do them carefully as to not aggravate the issue. 100% agree.
2) Honestly, I disagree but this is semantics. There is no substitute for squatting in the sense that one exercise will be as effective. You would have to do multiple exercises to get the benefits you would be getting from squatting. Which is fine, if that's what you prefer and you can certainly do it even without a leg press (One leg squats, jumps, etc.). But no, there is not another exercise that covers as much ground in one movement. That includes front and overhead squats, which one can argue are more beneficial that back squats due to the need to keep the body more upright. Elliot Hulse has a good video one this that I agree with. Both will expose your weaknesses immediately.
3) Disagree. Leg Press is not as effective as squatting in the sense that the benefits from one movement (balance, full body recruitment, range of motion, the benefits of learning to actually to a squat which no one seems to be able to do). The leg press in combination with other movements is perfectly fine and will lead to strength an muscle gains. But no, it is not a superior movment. No machine movement is. I would tell some one to do Double Kettlebell Front Squats first.
4) Totally agree. The whole growth hormone/testosterone thing is overplayed.