Sen0262 fluid type and questions of notes

I'm planning to use the SEN0262 in fuel tanks, and in water tank and in black water tank (sewage).

Does the sensor is safe to be used in a boat fuel tank considering the gasoline is highly explosive?

Does the sensor will work find in a black water tank considering that there is sewage debris?

One of the note says “The liquid level lead should be vertically downward”; if the sensor is not vertically and end up being horizontal at the bottom of a tank, would that be a problem or how it will affect the measurements?

One of the note says “Please prevent water from entering the terminal”; are you refering to the input of the “Air guiding tube”?

One of the note says “the joint is required to be waterproof”; which joint are you refering to?