About the same that can go wrong using gasoline.
Not true. Hydrogen boils at -423 F. Because of heat leakage into the tanks there will be a. constant steady conversion of hydrogen liquid to hydrogen gas. So you won’t be able to keep it in an enclosed garage without some sort of venting system. You also won’t be able to leave it while you go on a trip and Expect anything but an empty tank when you get back.
No, not really. The hydrogen must be under pressure, the gasoline does not.