Hm. Actually, the physics for power is... really mixed up. Pressure plates and switches can activate wires beneath them if there's one block in the way (which there always is, because the pressure plate/switch needs to rest on something) but not torches, and power torches can activate wires horizontal from them if there's one block in the way, power torches turn OFF if there's a wire or power torch one block DIAGONALLY DOWN (as in, one across, and one down) or two blocks down with one block in the way (but only if its a power torch) from them making it possible to make Inverter gates.
It is RIDICULOUSLY confusing!
Edit: Oh, and power torches can send power above it if there's a block in the way, so you can use that to switch rail tracks.
But only 8 times.
After that, the air block becomes bodaciously unusable for the same trick. Once a torch in that block is turned off, it won't turn on, no matter what.
Edit again: Okay nevermind that was just a bug in my session, for some reason. Disregard that.
Edit again again:
Here's an example pic I made of how underground circuitry works:
The position of the torch is important, btw. It won't work if its just resting on the block below.
Don't forget it works for T-junctions too.
Yeah, I am really interested in all this circuitry stuff now!