From my own experience
1. Remote needs to point directly at PowerMid top and within about 15 feet.
2. Explain better. Distance from remote control to PowerMid transmitter? Or distance from PowerMid transmitter to PowerMid receiver? My best from remote to PowerMID transmitter was around 15 feet. This is really dependant on output level of the remote. How far from the TV can you get your Harmony?
3. No. IR output is fixed.
My PowerMid receiver transmitted fine to TV about 12 feet away, in line with TV IR receiver window. The IR Extender (RX569) is ment to be positioned very near (i.e. in front of) the appliances IR receiver window.
Maybe.
What sort of lighting do you have in the rooms, incandescent or flourescent/LED?