Regarding some of your specific examples:
This seems like a bug rather than a "real" Android issue - Google Nexus 7 not recognized via USB
I don't really see why that's a problem. People sometimes encounter bugs when using Android. Trying to find a workaround for a bug (if that is the case) is a perfectly reasonable problem to want to solve. How is that not a "real" Android issue? What would be your definition of a "real" Android issue if not an issue you encountered while trying to use Android?
Did this break the rules? - What's the risk of installing Cyanogen Mod on unsupported phone?
Do you have a specific reason why you think this question is off-topic? What about it is not related to using Android? This seems like a reasonable question for someone unfamiliar with Android/CyanogenMod to ask before they dive in and get themselves stuck in a bad situation.
Too Localized? - How to connect your Nexus phone to a VGA projector?
I suppose I could see this being kind of a niche question, but I don't think I'd go so far as to say that it's "too localized". That close reason doesn't actually exist anymore as it is, but when it did exist it was generally intended for problems that were only reproducible in the environment of the OP, or questions that were (or would be) rendered obsolete quickly over time. On Stack Overflow a common use was for questions where the error was a typo. Anecdotally, I had my boss come ask me how to do exactly what this question describes before going to a meeting once (he needed to demo an app for some potential clients).
Now, regarding the general quality of the site: yes, we have over the course of this site's existence had a persistent problem with low quality questions, in my opinion. I think part of the problem is that there are a lot of questions that people want to ask that just don't fit on SE sites, which we have chosen not to accept ("Recommend a phone for me", "Help me find an app", etc). There's not a whole lot we can do about these other than to point people to resources that will be able to (possibly) help them, like forums and such.
We also regularly get questions that are just not answerable because they are too vague, usually with regards to bugs or other problems. "My messaging app is force closing. Help me?" is not descriptive enough for us to be helpful, for example. However, I would say that every site ultimately ends up with questions like this, particularly ones focused on end users (though, Stack Overflow certainly gets plenty of dev questions that are simply remarkably poor). Again, we just have to be diligent in keeping the site clean of these questions, and trying to guide the askers into posting more detailed questions.
In sum, I'm not really sure what the end goal of your post is, honestly. I personally don't find the questions you list to be particularly "fuzzy" in terms of their appropriateness, and you haven't really provided specific portions of the on/off-topic guidelines that you think need to be tightened. This makes it kind of difficult (for me, at least) to really provide much in the way of meaningful discussion on the perceived issue.
When you suggest:
Should the rules be made more clear?
...then I would recommend that you point out specifically the parts that you find unclear so that we can discuss them. Alternatively, perhaps you could explain what you think the appropriate topics of our site should be, and why. That would at least give us somewhere to start, but definitely do explain clearly the "why" so that we can accurately evaluate the merits of your stance.