My friend has checked out the people in ClickBank and if they are as good as they say they are. First of all the affiliate system they use does not guarantee you anything it is not sure you will get paid since it depends on if the person using your link or not the time of the buy. ClickBank cookies have been known to not work.
When my friend tried to get out the money he have made they told him that he need to sold something to one person from different credit card. If everybody was using Visa to buy for example he would not get his money. He has 300 $ to get out from them now and he still has not get any money since 6 month back.
I really think you should consider this before you dedicate to much time on them but sure if you sell you make good money but will you get them.
To answer the question that i got from one reader yes you can have Clickbank and Adsense in the same page.