Re: Google Adsense, referals etc
You don't need different codes for different websites. That I can confirm.
If Google suspects clicks are invalid, then you won't get any money. If you are clicking your own ads, or getting other people to click your ads, regardless of whether or not you are testing or not, it's against the Google Terms of Service and if you get paid, the money is coming from the advertisers.
As a previous advertiser, that becomes very annoying and people that do it should be reported to Google.