* Ads that appear at the top of the page are AdWords ads that have been sent up top (from the right hand side) by virute of having met an additional performance standard that focuses on the relevance of the Ads to Google's users.
* The CTR of the keywords searched is weighted more heavily than your CPC. So paying more doesn't directly help to get you there. Instead, focus on creating really targeted ads that Google users will find relevant to the search that they've done.
* You'll find that many searches produce no ads at the top. This means that none of the ads on the right have met the performance standard to 'Go North'. So, you'll see either zero, one, or two ads up there.
AWA