Actually earning is fully dependent on the add . If the bidder will pay less amount then u will get less money Try to use high paying keywords
Depends of the keywords your site targets. I have community sites and the average click gives less than 10 cents.
It's OK. Depends on the niche though. On one site I have 64 clicks for $4.66, on another I got 73 clicks for $15.31 and on yet another one I got 35 clicks for $11.28. It varies a lot.