if you site is getting traffic from asian or european countries and few visitors from U.S. Will google ban you for the quality of your traffic?
You'll be fine as long as your traffic is natural. Traffic exchanges, paytosurf, etc., is what can get you in trouble. Foreign traffic can pay less per click, and you are always subject to being smart priced, but unlike YPN, there is no problem with non-US traffic.
Google will mind only if your traffic come from PPC camp, auto-surf etc. You don need to worry if they are natural, i.e traffic from search engines.
Never. I have got a few sites that are India-centric and obviously most traffic is from India. YPN may have problems with such sites, but definitely not Adsense.