Trying to answer your question regarding the calls near the bubble. Reading on multiple forums and watching some poker on TV (the same as an average SnG player) it seemed to be that the strategy when you got to the bubble with a big stack was to constantly push and force the smaller stacks to put their whole stack (and any chance at prize money) at stake. Pretty soon people realized that with Ax or Kx they usually had one live card which is enough to stand up to the bully.