Success! 
I don't have the antenna mounted yet, but simply placing it on the floor of the attic and connecting the cable directly to the TV, I was able to get an "average" or better signal on ALL the channels I wanted to!!!!
A
very good feeling!
When holding it up in the air, all channels were "good" or better, but I don't know if my holding it affects the results (as opposed to the antenna just being mounted there). But I'll find out soon enough, when I do mount it.
Also, I couldn't connect it directly to the wiring distribution system because I discovered the end of the wire up there didn't have a connector, and I didn't have any around. But I fooled around with the distribution box connections a bit, and I'm now confident I can do what I want. I also ran a very long cable from the antenna to the distribution box and tried it that way. Lost quite a bit of signal doing that, though, and even an old amplifier I had around didn't help*. The bundle of wire up in the attic is pretty large (easily 50 unneeded feet), so worst case I can cut off the excess if I have to. I think it's going to all go together great.
Thank you
so much, mtownsend, for all your help! I'm ecstatic!
*Edited: It DOES help considerably, if it is inserted in the correct location. I realized after writing this that it makes the most sense to connect the amplifier to the antenna, rather than in the distribution box. That boosted signals one notch (average became good, poor became average, etc.). I still may not need it once the antenna is properly installed, but it's good to know I have the option if necessary. It's an old Radio Shack 15-1113A amp, up to 25dB (variable gain).