The answers are there but ill give you mine too: cold crashing is to get yeast out of suspension to get clearer beer. Get it as cold as you can for about 3 days at least. You don't need to warm it back up, but just keep in mind when you prime it for bottling that you don't have near boiling water with the dextrose and then add your beer directly to it. You'll want it to cool off a little first.
My opinion, homebrew is homebrew, it doesn't have to look amazing. Cheers