Understand Example of Nuclear Fusion Equation with Our Community

How does the sun burn in space as the sun is a ball of fire?

What are the advantages of nuclear energy?

"Mass and energy can neither be created nor be destroyed."
But if it is true then during a nuclear fusion or fission reaction how is mass converted to energy. In this case the mass is being reduced and energy is being increased. I know that it is due to the equation $E= mc^2$.
But does this violate the above quote?

When hydrogen nuclei are able to overcome the coulomb forces, two protons collide. As a result, one of them decays into a neutron and a positron and electron neutrino are emitted. However, isn't mass gained in this scenario because the the sum of the mass of a proton and neutron is larger than the sum of two protons?

Nuclear fusion does not occur with nuclei (with a nucleon number higher than 56) because the binding energy of the product nucleus is lower than the binding energy of the nuclei fusing together. Due to the product nucleus having a lower binding energy (and thus lower mass defect), this must mean that mass has been gained through the reaction which is impossible because energy is released?

What causes the mass of the two reacting nuclei to convert to energy and if it is for a purpose then why is it released. What is the source for this cause (if there)?

Why does fusion generate such large amounts of energy. If fission releases energy when some mass is lost as energy, then shouldn't the fusion process absorb energy to fuse nuclei together?

An under water explosion creates a bubble which quickly collapses on itself. The action takes less that 1/100 of a second for bubbles less than a foot across. This creates a point of extremely focused energy at the middle point where the bubble collapses. In theory, this point focuses enough energy to trigger nuclear fusion.
Could the same effect be achieved by suspending a metal sphere under water which contains a near complete vacuum. If the sphere were opened uniformly along all of its surface area, the water rushing should create the same effect as the explosion, focusing all of the energy on a point at the center of the sphere.
IF not, then what are the limiting factors (surface tension maybe?) In my mind, It seems the major limiting factor is the shrinking surface area of the bubble as it collapses. as the surface area shrinks, the water molecules along the surface of the bubble would resist the change of surface area (some would need move away from the surface, in the oppisit direction of the collapse), causing the collapse rate to slow.

I kept searching for answers or reasons as to why the sun can generate nuclear fusion at 15 million degrees C when I research that nuclear fusion is achieved at 100 million degrees.
Is it because the conditions of conducting nuclear fusion differ from one another?

Can electrons ever collide with other electrons during nuclear fusion? Or do they repel each other because of Coulomb's law?

What is it that make nuclear fusion so difficult at low temperatures? There is plasma existing at low temperatures, so what does it make for fusion to be so difficult to reach at ambient temperatures?

I got confused when I was researching about “neutron’s discovery in Chadwick’s experiment”. There was a nuclear equation said that when we bombard the alpha particles into beryllium, it will emits neutron particles as shown in this equation
${}^9\mathrm{B}\mathrm{e}+\mathrm{\alpha <!--\; \alpha \; -->}{(}^4\mathrm{H}\mathrm{e})\to <!--\; \to \; -->{}^{12}\mathrm{C}+{}^1\mathrm{n}$
What I am confused about is, isn’t the equation above a nuclear fusion reaction? As far as I know, nuclear fusion reactions require really high energy like on the Sun, but this experiment happens in a laboratory. So I wonder if nuclear fusion reactions can happen in laboratory, why can’t we use it to produce clean energy?

How do molecules having speeds many times greater than mean speed help in making nuclear fusion reactions in a laboratory?

Is the fact that Iron is attracted to magnets in any way related to the fact that it is also the element occupying the singular periodic table position where the chains of nuclear fission and fusion converge?
Or is this just a coincidence?

Why don't the nuclear fusion processes inside the sun produce ${\stackrel{¯<!--\; ¯\; -->}{\mathrm{\nu <!--\; \nu \; -->}}}_e$ despite having the same mass as ${\mathrm{\nu <!--\; \nu \; -->}}_e$? Is the reason as simple as "there is no production channel for ${\stackrel{¯<!--\; ¯\; -->}{\mathrm{\nu <!--\; \nu \; -->}}}_e$s." ?

Science project on the Sun. I have found that in order for nuclear fusion to work, it needs both helium 3 and 4.
1. Why can't nuclear fusion be done with just helium 4?
2. How can we create nuclear fusion on Earth?
3. Can we even do so?

Apart from thermo-nuclear reactions in the Sun, (and in hydrogen bombs and other methods developed by scientists) does nuclear fusion occur naturally in the planets? If not, why?
Also, do the Sun and the Outer planets - Jupiter through Neptune - have rocky cores similar to the Earth (consisting of iron, nickel, silicon etc) in addition to the gases? I have read that there is not much of hydrogen or helium in the inner planets because of their low escape velocities and the solar winds from the Sun. Hence only the heavier elements remained.

Birth of a star. Now in order for a star (or proto-star) to be born, there must be nuclear fusion that happens between hydrogen atoms. My question is what happens to the electrons? Sal never mentions them, only isotopes of hydrogen, and basically only focuses on the nucleus of the atom. Do the electrons even matter?

At the temperature range of ordinary fire or maybe even ordinary boiling water, is the Coulomb potential between light atomic nuclei occasionally overcome to give way to fusion?
Basically, how are the nuclear fusion cross sections calculated and are they a function of temperature?

Once the commercial nuclear power plant is built for electricity production , after this what kind of research does scientists do in nuclear fusion power. Why I am asking this question is ITER is planning to build the fusion reactor in 2030s , So after what research does nuclear fusion scientists do?