For sure, that against adssense TOS. So if you wanna try to do that, review their TOS first before you try it in your site.
Depends what you mean by 'popup'. If its something like a product preview window, sure. If it is annoying and unnecessary, no. A lot of websites use popup windows to show large sizes of small images - this is fine.
Yes. pop-ups are usually treated as blackhat seo. You can have pop-up but this can be penalty your blog. Actually just having pop-up is not against google TOS
you can use popup in any website with adsense! just dun put adsense inside popup and make sure the popup dun not block user to view the adsense banner! it should be fine and not against TOS... and make sure popup do not contain porn/other against TOS...