Evolution is random, it is not preplanned. I believe I am more of a Darwinist than you'll ever be. And given that you don't know what exponential growth is, also more of a scientist.Evolution is not random, again with the creationist arguments.
Well, that's rather dependent on travel times and how much they want to do it. Relentless expansion isn't necessarily a policy an advanced civilisation would take on. Plus, we do not know the lifetime of such a civilisation.
It doesn't have to be relentless. Colonization rests on a minority of explorers the majority stay at home cozily.