can i use any other PPC like Yahoo Publisher, Kanoodle etc. other than adwords to my adsense sites for traffic ??
Yes, you can use traffic from Yahoo Search Marketing, etc. You can even do it with AdWords...but if you have a low quality score then it can affect (negatively) both your AdSense earnings and your AdWords pricing.
Adsense doesn't care how you drive traffic to the ads. That is, doesn't care which PPC company you use. though according to the TOS they may care if you use other "methods" such as blackhat stuff. but within the PPC realm, you're safe, as far as I know.
Well, I begin to doubt that. Here is an example: Site one - pure organic and direct traffic - CPC from $0.3 to $1.7 Site two - cheap traffic bought from third tier PPC networks - 30 clicks = $0.7 ...