You can't find the exact value of the ads.. what you can do is add in channel and track your earnings to see how much a topic/niche pays off for you.
not possible. last month i have heard of such softwares, can't remember now but it is potentialy harmful
You can run adsense tracking scripts which are not against google TOS. Compare these to your channels. You can then get an Adwords Account. Between the two of these you get a pretty accurate answer.