This got to be longer than I intended, but there was much to cover.
I basically did the same thing you are trying to do, but I took two community college courses to get me started. Taking those two classes might not have taught me much more than how to expose and develop film and make less than acceptable prints, but it did put me in an environment where there were a few other serious students and we were all energized by our interactions.
So your question was, "what do they teach in school?" It depends on the school, and your interests—something you neglected to mention.
Maybe the most important thing school teaches you to be able to talk about (or defend) your work.
Another important aspect is that it enables you to think in different directions based on all you see going on around you. It might not have a direct influence on what you are doing, but indirectly, it is all important—either by planting the seeds for growth or solidifying your convictions about your work.
If you know how your camera works, there is no need for "assignments." If you want to learn about lighting, buy some lights and book on the basics and go to town (one definite benefit of school is having the tools at your disposal that you might not be able to afford on your own). If you want to learn non-silver then buy a kit and get to it. It isn't that hard—As someone else said, you learn by doing and looking. So do and look all you can.
As for what you should read? Not having at least a basic understanding of what brought about the world of photography as we now know it is inexcusable.
The short list:
1: Beaumont Newhall's History of photography. Yes, it is biased, but it covers everything you need to know up until the 50's. Then you can get into the Gersheim's or the Rosenblume's books.
2: Vickey Goldberg's Photography in Print.
3: As Tony mentioned, Liz Wells - Photo Reader & Critical Introduction are decent choices.
4: Robert Adams Why People Photograph and Beauty in Photography (those two books may help you solve all your problems immediately)
5: The introductions to any Photographer's books who's work you respond to. Go to the library if you can't afford to buy the books.
Then, if you are really courageous, you should read Sontag's books (I think reading that in the first term/year is just dumb and would have made me throw my camera into the ocean).
I'll address your last comment first. Exciting you is the absolutely most important thing you can do. If you worry about not exciting the viewer, whatever you do will not be true. And if it isn't the truth, then what is the point? In actuality, the more you work for/from your own excitement the more it will touch other people.
The ubiquitous "it's all been done before" comment is useless. There haven't been any real innovations since the 70's—everything has been repackaged. The sooner you move away from that preoccupation of making something "fresh" the better off you will be. Again, the only thing you can do is present the truth— whatever that might mean for you.
Just go out and see what is there. "Throwing paint at the canvas" is exactly what you are doing. But you aren't "hoping something sticks" you are discovering what sticks. There is no reason to think you should have it down after photographing for two years. That is what the formative years are for.
You don't know what to shoot? And you don't have a reason to press the shutter?
If you are really meant to be a photographer, then you will be driven to photograph, the world will provide that for you.