This question may seem strange, but still would like to clarify for myself. Is Newsstand framework required to use in newsstand app? I mean, can I make own issue model instead of NKIssue, download issues with ASIHTTPRequest instead of NKAssetDownload and so on? Or my app will be rejected by Apple?
I think you could make such an app, but I'm not so sure Apple would agree making it a Newsstand app. There are some things that may or may not be possible to duplicate (like silent push notifications for iOS < 7) but they are minor, depending on what you are after.
If you have it as a stand-alone app it should be ok, but then again maybe Apple will ask you to put it in Newsstand if it's a magazine-style app.
So the answer is, you are better off contacting Apple support to know for sure before starting your project...