"5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel." Not necessarily, it depends on the byproducts - hypothetically,

"5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel." Not necessarily, it depends on the byproducts - hypothetically, suppose when you burned the fuel the emissions were SOMEHOW 100% methane. You're essentially turning CO2 into methane in this farcical hypothetical, which is probably worse than burning normal fossil-kerosene. Obviously the emissions won't be methane, but you'll need to track the CO2e of every type of emission it produces other than CO2.