eCPM depends on the CPC and CTR. CPC again depends on the niche and the visitor quality. I will treat eCPM of 5 dollars as average. Anything below is bad. Anything above is good. But thats just me. No concrete stats are available.
Health, finance, travel ..... do a Google for the highest paid keywords. Dont go for anything too high though else you will never get any traffic . i.e. too saturated.
No bueno. Should be between $10.00 - $20.00 in my opinion. You just need to learn a little bit more about placing your ads correctly, using correct colors, and so on and so forth. Check out my sig and also be sure to check out Joel Comm on Youtube.