Black Hole Theory....Does A Neutron Star Possess A Critical Mass/ Boiling Point?

An ordinary star doesn't boil; it fuses elements together into heavier elements. A neutron star has gone past that: because of intense gravitational pressure, all it's matter has fused together into what is essentially a giant atomic nucleus containing only neutrons.

Adding matter to a neutron star will not undo the fused state that it is in, to start nuclear reactions again. It may start to add so much mass, that space starts to warp around it and become a black hole.

Yes, if all the stars and neutrons, and everything else got clumped together, you would have one big monster black hole. It's intriguing to ask what's outside of it, if everything is inside of it.

On the black hole's event horizon, time stands still, so maybe your fourth paragraph should read "zero time simultaneously with finite matter".

A neutron star is one of two, possibly three things. 1. It is the end result of the collapse of a large star, and is effectively a giant neutron. 2. It is a larger star on it's way to becoming something not observed but mathematically probable, and even denser, a quark star. 3. It is an even larger star on it's way to the ultimate collapse to a black hole. Leaving aside the disputed quark star phase, the main difference is that a neutron star is a physical, solid body, whereas a black hole is, in one sense, nothing. What is usually illustrated in books and TV shows actually the event horizon. This is a region of space surrounding the singularity at the center. The distance from the event horizon to the singularity is determined by mass of the black hole. It can be seen from this that what we call a black hole is not a hole at all, and many physicists prefer the original name of collapsar. Black star is an apt description of the phenomenon. It describes an object with an escape velocity exceeding the speed of light. The main problem for science is describing what happens at the singularity. At that point, and it really is a point, all that we know of physics breaks down, and cannot give us the information, because time stops, and gravity becomes infinite. We simply don't have the tools to describe infinity or the cessation of time, though many physicists and cosmologists are working on the maths.

Neutron stars have very high gravity, causing an enormous amount of pressure. As we know from Gay-Lussac's Gas Law, high pressure = low temperature. All of the matter rubbing together forms a great amount of heat, causing the pressures to balance out. There will be hydrostatic equilibrium. I don't think neutron stars can reignite.

You do not have a good understanding of what black holes and neutron stars are. Please do some more reading about the subject.