The wiki gives you clues, trial and error gives info and of course asking around...
http://aurorawiki.pentarch.org/index.php?title=CS_Aurora_Topic_IndexCivilian mining operations are no problem, send cargo ships with infrastructure and colony ships to the civilian station and use it as a colony site.
Are your patrol ship armed and in orbit?
About the population, if its over 10 million its being transported of planet by civilian ships, you can change that in civilian economy tab