I did the old loosen the shoe lace bit aswell! As far as getting numb feet on stair masters, I get that too (and on cross trainer). I'm not sure if this is correct but I have a dim and distant memory that my physio told me there are different "kinds" of numbness and that lots of people suffer the "stair master syndrome"! But apparently its not connected to the running pins and needles. Its all double dutch to me - I think I'll take the shopping tip!
I also suffered from this - every time I hit about 6km my right foot would start to go completely numb until I couldn't feel it any more. I went and saw a physio and along with the calf stretches already mentioned I was shown a stretch similar to a hamstring stretch (i.e touching your toes but sat down with your feet against the wall) but you slouch your back and put your chin on your chest. Really push down (yes it hurts!!) and do four reps and hold for a count of seven. After a couple of nights I was pins and needles free!!