If you're doing less well than last year, the reason is probably simple: More publishers are competing for clicks. AdSense revenues may be growing, but the number of publishers (and those publishers' pages) may be growing even faster.
Surely. It's 2007. How many businesses aren't online yet? How many of them that are online have never heard of Google AdWords? Most firms have limited options online, so they probably have at least tried AdWords by now and continue with it if it's converting.
That leaves new clients coming from new businesses (and arbitrageurs). The rate of new firms starting up is much lower than the number of new websites and MFAs starting.