Russia has weighed in on the side of the Shiites. ValJar is Shiite. Huma is Shiite. Iran is Shiite.
Saudi is Sunni.
Russia would go back home tomorrow if the price of oil went back above $100/BBL. Unless and until that happens, the Russians will continue to plan and equip for the invasion of Saudi Arabia.
From there, the Iranians will insist upon the invasion of Israel, which is where things will get interesting.
Wrong. Russia keeps a fleet in a port in Syria and has substantial trade and commerce with them historically. It is not about oil.