Forum Moderators: martinibuster
1) Most people aren't saying (either because they don't want to or because it's a violation of Google's AdSense TOS), and...
2) Earnings vary from a few dollars to many thousands of dollars a month, depending on the topic, traffic, and any number of other factors.
The only way to find out how well AdSense might work for you is to apply, be accepted, and test AdSense on your site. (Fortunately, Google doesn't require a long-term commitment, so if you don't like the results, you can pull the AdSense code from your pages.)
The only way to find out is to sign up and try it. As EFV says, it's not a lifetime commitment - if you don't find it's worthwhile doing then just remove the adsense code from your pages.
Once you have signed up, there is plenty of help and advice on how to maximise earnings here. You need to try it for a while before making any decisions.