Providing the adsense is not on the pop up. But why irritate people with pop ups? Not that it irritates me since my pop up blocker takes care of those.
Used to be no, but now it's okay. I think they allow a maximum of 2 pop-ups on the same page as Adsense ads, in fact.
The same people who provide good (which I'm assuming you mean high-paying?) are the same people who provide good CPM banners -- TribalFusion, Fastclick, Casale, etc. Those are the top 3 everyone shoots for. Failing those, you can go with Burst Media (which I personally wouldn't recommend, as they seem to be on their last legs these last few years), or any number of second/third-tier CPM programs. Failing all the above, you can go with the more infamous pop-uppers, but then again, your chances of getting paid by these guys are about the same as getting hit by a car, so.....
Impressions = CPM (paid per 1,000 impressions). I.e. each banner network gives you a rate (according to how much the advertiser is willing to pay) in which you'll be paid that amount whenever you've served up 1,000 impressions (i.e. the ads show up 1,000 times). It doesn't sound like a lot, but if your site is a high volume site, and gets a lot of hits, it'll result in a nice pay every month. What kind of site do you have?
Directly from adsense Policies (https://www.google.com/adsense/policies): Site Content Site may not include: [...] * Pop-ups, pop-unders or exit windows that interfere with site navigation, obscure Google ads, change user preferences, or are for downloads. Other types of pop-ups, pop-unders, or exit windows may be allowed, provided that they do not exceed a combined total of 5 per user session So as long as you stick to that you'll be fine. You might want to ask the adsense team if it's OK after you've made it. If your site is the kind that has regular returning visitors you might to want to do some "research" (a short questionnaire or run several polls) to find out what they like/dislike and how many use pop-up blockers. From this you can also establish what kind of ads interest them and then make any ads you run more targeted to your audience. EDIT: The google adlink unit for this thread is (at the moment): Ads by Google Kill Pop UPS Pop-UPS How to Disable Pop-UPS Pop Blocker