All of these are huge unknowns, and anyone who tells you they have answer is lying and/or crazy. A few before oil started to drop, many leading analysts said the absolute lowest they could see oil dropping in the near future was around $90/barrel. I promise you when I say no one saw $45/barrel coming.
No one saw the Depression coming. No one saw the Recession coming. No one sees the next bubble nor do they know when that bubble will burst. So the question you need to be asking yourself is not whether we have hit bottom, but are the investments you're looking at trading with a significant margin of safety? In other words, if things can get even worse, how bad will my investment perform? Can it go belly up? Can it withstand a long decline in oil prices? Some of the fracking guys who took on a lot of debt probably can't operate at a profit with oil so low. But others like Exxon, who have huge barriers to entry, a giant global infrastructure, and a diversified business could even emerge stronger.
But yes, I do own XOM stock, and have bought more over the past month.