Really? I was under the belief that gravity will eventually pull the galaxies together, with the Milky Way and Andromeda merging in a few billion years time.
The universe is expanding, the space between things is growing, think of the universe like a balloon with the stars dotted on it, as you expand/blow up the balloon they get further apart.
Eventually the expansion will overcome gravity, it may big crunch, I am speaking in exactness, the big rip appears to have more evidence.
You are correct, some galaxies may merge, this is only in galaxies which share the same gravity well, in an expanding universe, all things are moving apart.
AFAIK the speed is proportional to the galaxy distance. For this reason the redshift is used to estimate the distance of the stars
Hubbles law correct?