Agree with most of it. I have found Dave Tate and Louie Simmons have some really good points about squatting that do apply to some raw lifters - me, for example. But, you do need to constantly bear in mind that their advice is meant for geared lifters.
The main thing I found they got right was that wider tends to work better than narrower - just for raw wider doesn't mean multiply wide. The whole vertical shin idea isn't so great for raw.
OP, with your issue of the bar falling just lean forward a tad more as you set up and hold that trunk angle throughout the squat.
Bottom line, if you squat heavier with a higher bar and closer stance there isn't any real reason to push yourself to squat wide with a lower bar. If you do want to just learn how, I'd recommend wearing wrestling shoes or Chuck Taylors and trying some box squats to get a feel for the movement.