This is going nowhere. Your just restating what I already stated, then pretending to correct me.
This is the difference between Newton and Einstein physics. In Newtonian physics matter and energy can be neither created nor destroyed, both are conserved and only can be converted from one form to another.
The ability to convert between mass and energy is a characteristic of relativistic mechanics, not classical mechanics.
A gallon of gasoline has a quantifiable amount of chemical energy present, upon being exposed to an exothermic reaction (combustion) it will release that energy in the form of thermal and kinetic energy.
Exothermic reactions release energy in the the form of heat or light. You could argue that since temperaure is the average kinetic energy of the atoms of the substance, but generally speaking you would simply state thermal energy.
The matter that is left will have the exact same total mass and elements present only now at a lower energy state. That is a Newtonian reaction.
No, that is a chemical reaction.
Einstein discovered that matter and energy could be converted between each other as a result of how subatomic structures work.
The results of his research was the famous formula E=MC2 which is the conversation rate between Energy and Matter with the speed of light in a vacuum acting as the coefficient.
No, the Mass-energy conversion was discovered as a result of how (for a lack of a better term) galactic structures work. From what I recall, it had to do with resolving problems with inertial frames.
In a nuclear reaction you take a specific amount of matter and after undergoing nuclear transmutation it comes out as a different element then it started with less mass then it started with. The amount of mass it lost was converted into energy in the form of high energy radioactive particles or radiated energy (x-ray / gamma ray / microwave). In a nuclear fission reactor you feed Uranium MOX (Thorium is on the rise as a next gen cleaner fuel) into a chamber where it's bombarded with slow neutrons, eventually the uranium cracks and creates more neutrons that cause more molecules to crack which results in a bunch of high speed particles exiting the moderator and hitting into a thermal wall where it's kinetic energy is converted into thermal energy. When the fuel is finished cracking your left with various low energy unstable elements that continue undergoing radioactive decay, their total mass is less the the original fuel mass.
This is broadly accurate.