Yes you can do both. Here is a quote from the Ad Network TOS "Co-op ad network ads should be the exclusive ad network used for that site. This means those sites are not able to utilize a similar advertising network (Google AdSense and other contextual ads are not considered similar). The main reason for this is to prevent users from overloading their own sites with ads and diminishing the overall quality of the sites in the ad network."
sure can. adsense and co-op network are very different. co-op adv just like normal link like what you see at you blogroll