What else would I need, a CM 7777, a rotor, and some sort of combiner?
You won't need a combiner, the 7777 will combine the uhf and vhf antennas for you. Just make sure the internal switches are set properly on the amp (instructions are provided).
You can try it without the preamp first, if you want. In that case, you will need a uhf/vhf diplexer. CM makes a good one, I think it's designated 0549 or maybe 0547. If your cable run is >50 ft. though I think you'll benefit from the preamp esp. for the uhf channels.
There's a dealer for Antennacraft in Johnson City FYI (that's where I got mine).
I wouldn't worry about the power lines, just stay away from them while you're installing everything! You'll probably have to experiment some to find the optimum height. In general, higher is better, but not always.
The CM9521 rotor is available at Lowe's. Good luck