Creating a channel will only let you monitor your revenue coming from that particular channel. The relevancy of the ads will greatly depend on your content. Or, you can also target using Section Targeting. Refer to the link below on how to implement section targeting, but don't overdo it.
Code:
https://www.google.com/adsense/support/bin/answer.py?answer=23168
Or you can refer to Joel Comm's Adsense Secrets on this thread below. On that ebook, there is a topic about section targeting.
http://www.blackhatteam.com/f51/get-...tml#post228096
CTR will depend on how relevant your ads to the topic/post on your blog or site and your Ad Placements.