Thick white smoke gas gauge dropping

So I just bought the SUV a few weeks ago, and the engine runs smooth as can be. However I have noticed I get around 6 - 8 MPG (I thought it was because the brakes are sticking, but that's another story for another day) on the way home from work I got a low oil level message and was close to empty on gas but was tired so left it for the next day. When I went to start the SUV I got crank but no start. After draining my battery and recharging it and adding oil (dipstick showed almost no oil) the SUV still would crank but not start. So I got a friend to tap on bottom of fuel tank (trick I learned years ago for a failing fuel pump). It started instantly but produced white smoke and the front seat smelled like gasoline. I drove a loop around the block and the white smoke got thicker to the point I was surrounded by white smoke at a stop sign and it developed a rough idle, and the fuel gauge went from a notch above empty to a notch below redline in less than a mile. I checked coolant, it's clean smells like coolant and hasn't dropped at all, but the oil though clean is twice as high as the max line. I checked spark plugs wires and noticed one was barely hanging on by a thread. Replaced it. Question is, could I have had a false indicator for low oil and now I'm burning excess oil or is it more likely fuel got in oil from a stuck open injector causing the high oil level and white smoke?