"Ever since ive gotten this car, the temp gauge in the cluster never worked (always rested at the bottom). could that've possibly played a roll in the roughness of the car?"

I would replace the thermostat. Who knows, maybe there isn't even one in there. A thermostat stuck in the open position will make the car run too cool and won't burn off the moisture that naturally collects in the oil. This would be the reason for the milky substance in the oil. This could also lead to the reason why your temp gauge doesn't move.

Also a malfunctioning PCV valve and plumbing will cause milkiness in the oil. With the motor running, pull the PCV valve out of the valve cover and make sure there is vacuum at the valve. I usually give the valve a shot of carb cleaner every once in a while to keep it from sticking.