Wow---Youve got a lot of questions...Let me help you with a few....You forgot to mention DARK FLOW>>>Scientist seem to use the word DARK for things that they have trouble explaining, but know that they exist. All galaxies would fly apart using the existing gravity that they have---Black Holes do not contain enough gravity to hold most galaxies together. They have calculations to prove this...They have also tried to simulate the existing galaxies on computer programs using the existing gravity that they have. They would all fly apart. They then added extra gravity. This solved the problem. The extra gravity (which they say is everywhere) is called Dark Matter. The galaxies would then end up in the sprial that they are most in, using this Dark Matter. Galaxies also spin around a black hole...The reason that they are flat and sprial, is the same reason why a pizza maker throws up a circle of dough and spins it...It then becomes flat.
Dark Energy is the UNSEEN FORCE that drives our galaxies into their never ending expansion. Scientist do not know where Dark Energy comes from...I actually think I do...Please read my "discussion" theory on Where did the singularity of the big bang come from... thanks jay