In the airline industry elevation = height above ground and altitude = height above sea level. Altitude is used to calculate air pressure, elevation is used to make sure you don't crash into mountains.
Marijuana is a dangerous and addictive drug that has many consequences to using it. People debate whether it should be legalized or not due to its pros and cons. Marijuana should not be legalized because it is a gateway drug to the legalization of other drugs and has many bad effects on the users of it.
Very possible, some states allow it for medical purposes. The process may take quite a while, but there it is likely that marijuana will be legalized eventually, as the laws become more and more relaxed. No, because pot is so easily grown that the government won't be able to make money from it.