They do. Clicks generated though you telling people to click on your links or through clicking the links yourself = against tos
Yeah. They have. Google defines invalid clicks as: - Manual clicks intended to increase advertiser's costs or to increase profits for website owners hosting your ads. - Clicks by automated tools, robots, or other deceptive software.
Don't forget also anything that indices the users to click on the ad, therefore making it invald (things such as the text "navigation" above the ad unit)