yes you can. The only combinations you can't make with adsense is contexual ads. Ads that are dynamicly driven based upon your site. So yahoo publisher ads can't go with Adsense but affiliate products and links from fi cj, linkshare, maxbounty, shareasale etcetc are totally no problem.
I believed that the lightened up with this. I think they allow contexual in certain cases. Kontera and AdSense is okay now, primarily since the ad style is different. Also widgetbucks and adsense is okay (and they have a contextual ad format). I think where they draw the line is if the contextual ad looks like AdSense (ie: Yahoo, MSN, etc). NazStory - you may want to carefully think about placement of your AdSense. Some people would advise against AdSense and CJ because you're sending visitors away for pennies vs dollars in commissions from CJ. I personally like a blend of the two, but low emphasis on AdSense (ie: at the bottom of the page and only one ad unit). I blogged about this the other day - "Googel AdSense with affiliate store font (good || bad)" hanji
Yes you can. There is no problem in doing so. But try to place those ads in such a way that visitors would be more interested in those products earning you dollers rather than clicking those adsense making you some cents.
I wrote a report about this. I don't since the visitor clicks away from my site. Thus I trade a potential big commission for a .10 click. That SAID I do put CJ on my adsense sites. But by CJ I do not add adsense.