Lots of theories and ideas. Here is another one: The oil issue is a result of global reduction in usage of fuels and a strengthening dollar. Vehicles are getting better mileage combined with people traveling less (at $3.30 per gallon gas). As the cost comes down, peoples habits will change and may be more inclined to purchase vehicles with worse mileage and or travel more. Time will tell.
Another factor is the middle east oil economies. They see the US as a nuisance and are willing to lower pricing to counter US production. Actually, our production is fairly cheap ($30-$65 per barrel depending on landowner agreements and the cost to drill the well), shipping via rail cars is terribly expensive = $2 per barrel via pipeline and $15 per barrel for rail, so you have to factor that into market selling price of crude. While the US has large energy reserves, they are largely landlocked and restricted to the available rail routes and refineries. The middle eastern oil economies are the ones that dictate the price of oil and they will for a long time to come. They can easily tolerate lower pricing to slow US development.
As far as Russia, they and other countries have scented weakness in the US and in Europe and are taking advantage of it. Russia would not want a war as much as we would not. We all have too much to lose, but if they can get some benefit, ally, territory, push just a little and the west usually backs down. Europe will be the first to break their own sanctions, as they always do. Their economy is headed down and they do a lot of trade with Russia and will need that to move forward. Russia will always have an energy stranglehold on Europe because of the natural gas, no other way around that, especially since nuclear energy is being frowned on.
The next problem is the US dollar. The US led the world with currency weakening to boost our economy. While it is strengthening now after all of the weakening that was done, other countries are weakening theirs to boost their economies. So starts the currency wars. Soon the US will not be competitive on the global scene and will have to weaken the currency again to catch up. Not sure where it stops.