I'm not sure why you say Taz's response is useless. He's explained a few points to you, including the one about the relationship between not knowing much about something and it "not sitting well" with you. There's a wealth of information on astronomy to tap into on the web.
For one thing, why should two galaxies colliding make the universe slow down in its expansion? The whole of space-time is expanding, carrying matter and energy along with it. It matters not what the matter and energy are doing, they do not prevent the expansion of space-time. Dark energy seems to be causing the acceleration. You can read about it
here.
About the idea that the universe could have originated from a black hole. Some people have suggested this. It does seem that the universe started out as a singularity, a point almost infinitely small and infinitely dense. A black hole is also a singularity, albeit of much less mass (the largest so far detected contain the mass of a few million suns). The problem there, though, is that the universe
exploded. You would have to come up with a mechanism that described how a black hole would suddenly explode, when every black hole yet observed has only
consumed matter and energy. Black holes are believed to emit something called Hawking radiation, but it would take billions and billions of years for a black hole to radiate all of its mass in this way; it is a very slow and gradual process.
That isn't to say that some brilliant mathematician might not be able to describe one day how a black hole could theoretically explode. Maybe Dr. Adequate will stop by and share some of his insights.
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