MDA is a man-made (synthetic) recreational drug noted for its stimulant and psychedelic properties that has been used since the 1960s as a clubbing and sex-enhancing substance, with some similarities to LSD and MDMA (ecstasy). Sought after effects.
The soaring temperatures that Las Vegas is experiencing this week could cause grief for pilots at other airports, because heat thins the air and makes it more difficult for aircraft to lift at take-off. To deal with that, pilots need to gain more momentum as they roll down the runway before reaching liftoff speed.
When aeronautics was in its early years people with daring took on as much fuel as they could to fly over great distances with quite inefficient engines. I suppose the answer is: an airplane can hold as much fuel as the maximum take-off weight for that particular plane is. Of course, getting extra fuel tanks in there, and connecting them to the intake is huge work, and I don't think people much do long-distance flying with small planes these days, since all the records have been set, even for a non-refuel flight across the world.