It's just one training method that people use for box squats. When it comes to back squats they are talking ultra wide stances and yes, it is a powerlifting, or in this case what everyone refers to is a WSB style squat.
There are prob vids of Dave Tate doing it or something.
No, not everyone has to do it that way or would want to.
You sit back more and the torso will compensate. It increases the spinal compression a great deal. In fact it is why a lot of coaches criticize box squatting. There is always more than one way to skin a cat.
Here is a vid of the kind of thing people are reffering to. As you can see it has little to do with the way you train:
You can also see the compensatory sit back on the box which is one of the big criticisms. As you can see it is a very wide stance and low bar squat.
Boris actually has a good vid of more this style of box squats with some good tips and kudos on the squat rx thing.
And here is a Defranco training vid with a regular box squat. More neutral back position, narrow grip, prob a tad wider than normal stance...
And here is a link to a guy doing some front box squats. He is using straps for handles like I explained about before. These are perfectly good front box squats.
Sorry, hits...but anyways I know you like vids