Re: Knee crunching with straight feet in squat
First off, feet straight(ish) is what Kelly and crew recommends. I believe he said something like 5-12 degrees. The more straight the feet, the more torque you can create at the hip. Test it for yourself: stand with your feet straight, plant your big toe in the ground, and squeeze your butt and quads. Do this again with your feet pointed out a little bit, then again with them exaggerated (like 45 degrees or more). See if you can tell the difference. And as Carl states in his book, free+style, the wider your stance is the more your feet will turn.
It all comes down to maintaining a stable foot, stable hip, and stable spine.
Now as for the crunching, I would ask what your purpose is for squatting? The answer to that may be different from week-to-week or session-to-session, but it is something to think about. To me, by squatting with your feet straight(ish) you are reinforcing a stable position that will eventually translate into other things.
I would recommend cutting your weight and range of motion for most workouts so you can gradually build up the mobility to get "full range." And in the meantime, work on mobility for hip flexion + internal rotation, ankle/calf/bottom of foot, and terminal knee extension.