Ok from what I know if you pick a low competitive niche with a low cpc keyword you will get less when ppl click your ads. Im assuming google reads the content of your site and displays relevant ads. However what if you threw in keywords that are similar to a high cpc would you not get more high paying clicks then? for example your site is mainly on a low advertising cpc like football for example and if you through in some high cpc competitive keywords like betting or something would google not give you some beting ads which will be worth much more per click?
Yes it does happen, however just cause you put in high keywords doesnt mean you going to get a high CPC
The way it works is that Google reads your page and determines a theme to the page. Actually, it probably determines a few themes to your page. It then tries to match your page's theme(s) to the theme of an advertiser based on their keywords. There are a few problems with this. One is that many advertisers just don't do things that help the system determine the proper theme. They don't learn the system much and do things the quick, easy and lazy way. Of course, as a publisher, you have to help the system along too as much as you can to help it determine your page's theme. Proper page title, description and content related to what your title and description says will go a long way. The keyword tag may also be used for this although I'm not sure if they do. If I was Google, I certainly would.
Google bot analises content of your page and shows relevant ads plus it analyses most populat users requests and makes ads relevant to them
I believe this comment is related to adsense as opposed to adwords (unless you are talking about keyword scoring, which I don't believe you are). Google has made their mark on the industry by revolutionizing the way they index the internet - determining what a specific site is about is just part of what they do.
Spyfu.com is an excellent tool for researching PPC metrics like CPC, advertiser competition, and more. Otherwise start small and be conservative, than you can start to work your way up in bid prices and budget amounts. Start slow, you can lose your shirt quickly in Google AdWords.