Raptor this is the broomstick lunge deal I was talking about:
http://www.youtube.com/watch?v=4IGZTVInH1Y
Make sure you keep both your feet on a line.
As for the front squats you should be able to do them without even touching the bar. There is a groove between your delts and neck the bar will naturally sit. Check this out:
http://www.youtube.com/watch?v=WE81-EtbqcA
I actually do them unloaded a couple of times per day...no bar or broomstick I just "pretend" like I'm holding a bar - the effect as far as thoracic mobility is the same. If you do a lot of sitting the front squat is the best exercise there is to cure bad upper body posture IMO.
Hm... to quote another commenter - is the knee supposed to go as far in front in that broomstick video? How far should I step back with the "non working leg"? As far as possible but that I can still go straight down?
As for the squats - I can go pretty low both in the normal squat and in the front squat but only if I take a very wide stance and rotate the feet quite a bit to the sides. For example, in that 145 kg squat video I posted I had a very wide stance, I think more than 1.5 x shoulder width... otherwise I wouldn't be able to go so low (low = parallel or so). I'd just fall on my back or I'd have to compensate by bending forward.