Better search for the fuel leak before you have a fire. A mist suggests the leak is from someplace where the fuel is pressurized, not a return hose to the tank. Look where you see the mist coming from. That can be all the way back to the tank. The leak will cause the fuel pressure to drop when you stop the engine. That will cause a long crank time. The pressure builds slower than normal during engine cranking and it has to reach a certain pressure before any fuel will spray from the injectors.