Pianoperformer: sorry, I thought this blog was an "extension" of your "musicalprogress.com" idea from the other thread, where you'd specifically mentioned making a profit. But my overall point still seems valid, that you are beset by what are relatively small technical details because you don't actually know how people would benefit from your blog. In which case, it's in danger of being more of a vanity project than anything. (Though you could, arguably, benefit in a sort of "therapeutic" way from the catharsis of an online journal....)
As for your most recent question (in the last sentence of your most previous post), I don't think readers would be "confused"...and if you "packaged" your blog right, from the outset, I don't think they would be "annoyed" either.
To package your blog for multiple themes, make sure to signal that fact prominently, either in the URL ("my-wisdom.com") or as a site slogan ("life, the universe, and everything -- plus the kitchen sink").
Think of all those great movies or novels which explore multiple issues...sure the simple folks get confused or bored by such fare. If that's who you're talking to, well, you might well keep things simple and straight-forward and just stick to chatting about the weather!
Ultimately, a writer is an entertainer (and bloggers are just writers -- often very poor ones). If you take a creative writing workshop, where your stuff gets critiqued, you'll get that notion in your bones (though the word "entertainment" would probably not be used): your job is to entertain, to keep them turning the pages.
Hey, look at Steve's blog. What's he doing here? He is entertaining people. That folks may learn a thing or two is really beside the point, whatever his own intent. People might first discover the site while searching for some kind of "information," but they return because of the entertainment (and, incidentally, the genius of an online forum is that your visitors create entertainment value for you -- for free!).
You see, you may or may not be able to get a point across to someone -- that is, teach them (though, a bit like Socrates, I would say that there is no such thing as teaching, only learning) -- but you can always entertain someone. Really, even the mentally handicapped can be entertained. Even most animals. (Not that the mentally handicapped are animals, mind you.)
So how's your blog going to keep people amused? Whether intellectually or emotionally (though distinctions are artificial and there can be no "intellect" without "emotions"), your job is to entertain.
Think of how you entertain your audience as a pianist. Would they be confused or annoyed by a broad repertoire? Not if the advertised point of your show is to demonstrate a range of styles, say. Likewise your blog. You may perform badly, but any displeasure resulting from that wouldn't be on account of the breadth of the attempt, but from the incompetency or superficialness of a particular performance.
Do you know how to seduce women? If you do, you should have no problems as a writer (or, for that matter, politician or dictator!). It's the same psychological mechanics involved.