You can read Adsense terms and conditions and you will know about reasons Adsense bans your Adsense account
Although it is very simple to say violation of google TOS will get you banned, you should know each and every point of the terms of service in detail to be safe.
"Adsense account disabled" phobia increasing day by day. Just read their TOS and program policies and comply, you will be fine.
the number of adsense account getting disabled is directly proportional to the number of stupid ass DP noobs joinining the forum
the "russia ban" probably has to do with the amount of fraud involved. I seriously doubt Google would ban accounts without good reason as it provides them with steady revenue streams.
Invalid Clicks and Impressions Traffic Sources Site Behavior AdSense for content. Up to three ad units and three link units may be placed on each page.
Read their T.O.S and you will understand the dos and dont's. I have also written an article about how to avoid getting banned by adsense.