As far as difficulty -- it auto adjusts every 210000 blocks. If it's sky high and people stop mining it'll take a very, very, very VERY long time to adjust again.
False, every 2100 blocks. Which is roughly every 12 days. Next difficulty in about a week. Probably will be around 800k.
Difficulty can also drop if enough people drop out. At these prices though, I highly doubt people will drop anytime soon. If the market tanks we will see people dropping out.