Not really. Not in most cases. Unless they claim that the content is purely theirs and that the content is of vital importance.
No... You won't be banned unless it was reported by the original content holder to Adsense. Most of the webmaster will send a mail to the duplicate content provider that he would intimate the adsense to ban the site/ban. In spite of this warning, if the content is being duplicated, you will be banned.
If the articles are meant for distribution, Google will not have any problem. Many sites use duplicate content. As long as there is no copyright violation, you can publish any content.
Yes, they do and I have just one website that was penalized for this and it's been a year since I removed the duplicate content and re-applied but so far, only the AdSense Ads got back on my site after getting removed as part of the penalty. Now, it is still not in the Google index. So avoid it while you still can.
there are too many duplicate contents on the network. im sure google has other better things to do than check for duplicates.