Yes. Read my second sig link, question #8 if you want an explanation that will answer that same question for Adsense + any ad network. Good luck!
Yes you can. But dont use it. It steals your adsense clicks and it pays meger compared to adsense. So if you use kontera you loose some bucks. this is my prediction...
Sure, you can use Kontera along with AdSense but you have to make sure that your Kontera ads did not share the same colors and styles with AdSense. Google AdSense TOS did mentioned that they don't want see other third party ads have the same colors and styles with AdSense ads.
it's fine to use kontera, but it's better to have a high traffic site (when is it not?), and make sure you limit kontera to display links only on the content part of your site, and you have all adsense above the content, that way if user hasn't click on adsense, then he can go to kontera. Kontera ecpm is poor, but used like I said it's additionnal money and won't impact adsense CTR.
You can put any other ads on pages with adsense ads, as long as the other ads do not look similar to adsense ads.