Sorry if this is too complex, boring or non-word-related.

Einstein was the first to propose the presence of black holes. The theory arose from his calculations around the relativity theories. "Objects" which act in the way Einstein described have since been "observed" in the universe. The support for the existence of black holes developed, in large part, due to the fact that Einstein was considered pretty smart, and was right most of the time. His calculations also suggested the "singularity" at the centre of a black hole. More on that later, maybe. It also pays to remember that much of this is still theory, despite its wide acceptance.

a) if the hole is just blackness how do they know that there is light in there that is not escaping? If there is no light seeping out maybe there is no light at all.

I think this was succinctly answered elsewhere. Basically it should be emitting radiation of some sort, but it appears not to be. Technically the event horizon is the point from which light can not as opposed to does not escape.

b) how do they know the laws of physics do not apply inside black holes? No one or no probe has ever been in there to send back info.

Again, this is Albert et al at work. And it depends which laws are being applied. Rather than laws not applying, it is more likely that laws and forces we are yet to decipher have such an overwhelming impact on the situation that the the laws we know can not explain what is happening. The concept of a singularity is a pretty damn confusing one, and I'll leave you to your own reading to make sense of it.

c) if there are places where the laws of physics do not apply can they really be called laws?

Short answer, yes. Long answer, see previous answer.

d) how do they know the inside of a black hole is infinitely dense - again, we've never been and it could be something else completely PLUS if something is infinitely dense doesn't it follow that nothing could be sucked into it since well, it's too dense and there is no place.

Ok, this one could be difficult. Infinitely dense is probably a simplification of the situation. Einstein's maths suggested that stuff just keeps going in and well, yeah. Your argument (or something similar) was the basis of the 'portals to somewhere else' theory. The stuff can't just stay there because it's too dense, hence it has to go somewhere else. Well, that associated with the whole space-time curvature thing. Does it help if you think of the universe as both infinitely big and infinitely small in the middle of a black hole? And infinite does not just mean really big, it means, well, infinite. And you'd be travelling at the speed of light, which means you'd be infinitely big.

I'm pretty sure that last paragraph wouldn't have helped much.

e) Portals into other universes???? It sounds exotic, and wouldn't it be nice, but how did they come up with that?

See previous answer.

I mean, why would they assume the far end of a black hole is not occupying same area of the universe as the near end? For example, if I cross the St Hypolite tunnel in Montreal Québec, I go from Montreal to Longueuil in Québec, Canada. I don't wind up in China.

I'm assuming the speed limit through the St Hypolite tunnel is not 300 000 000 m/s (1 080 000 000 km/h, 675 000 000 mph). And that your car is not infinitely massive. And that space is fairly undistorted and that time keeps ticking away at 1 second per second. And there's no 'far end' to a black hole. Just a middle. If you're in the middle of the St Hypolite tunnel, you could theoretically be anywhere.

Why is that assumption being championed by so many scientists? Is it wishful thinking? Or does it have as much validity as someone advancing the theory that when someone goes through a black hole they come out being born on the other side as a new baby.

It probably has a little more validity that the baby theory. Time would be distorted in much the same way as space, but distorting time only makes you age faster or slower, it doesn't reverse the ageing damn crossed thread process. I think I covered the reasons for it's popularity above.

How is it possible that a black hole appears to emit particles when we know that nothing can escape from within its event horizon?

When matter and anti-matter combine, they create well, nothing, basically. Similarly, nothing can spontaneously create matter and anti-matter particles. This happens continuously, although the particles don't last for very long and they pretty quickly combine to create nothing again. However, if this happens near the event horizon, and one particle enters the black hole, the other will (following the laws we know, which work well outside the event horizon) shoot off in the opposite direction. It is these particles which we can detect coming from where nothing should be able to come.

Any more questions?