There's lots of chatter if you search around this site on that. It seems like many of us lean towards just leaving your beer in primary for 3-4 weeks then bottling or kegging unless you are adding fruit, oak or need to age the beer for a long time such as for a barley wine or other higher gravity beer.
It is a personal preference that you will need to come up with. You will find that some folks call a secondary a "clearing vessel" or something similar. With a Kolsh, you probably want a clear end product so a secondary is likely a good idea, but not mandatory. Totally up to you. I have not found a reason to 2ndry other than those listed above.