Everyone always says to have ads above the fold for best CTR, but my best performing link unit is actually at the bottom of my page. Keep in mind that this page actually gets read, so most of my visitors scroll all the way to the bottom. Then they see my link unit and click for more information. This strategy usually outdoes all my other ads put together for CTR.
Yes not all sites will be able to use the hotspts as the best placement for adsense ads. Your experience just reaffirms the need to test different placements until you find the one that converts the best.
I presume you are talking about the tips website in your sig and yes the ad placement for an article/tips site should be at the bottom and text/article wrapped around ad unit (assuming your articles are interesting enough).
Right. There are two ways to get a click -- annoy your readers so much that they want to just get out and never come back (ad near the top) or give your readers a reason to stick around until the article's end and then place an ad so they can find a relevant product to browse and even buy.