Limiting use of Pilot Controlled Lighting

Having just crossed the border, and visited a few non-towered airports
in the US, I'm afraid I may have done some injustice by using the PCL
pilot controlled lighting a bit too much. Knowing the somewhat
precarious financial state of those airports, and the electricity hog
the lights can be, I'm wondering if its use is required at all. Can
the USA procedures experts here please comment on the following?

1. Any legal requirement to use them during the day (that is, any
FAR)? Is it an AIM recommended procedure?
2. Will 3 clicks ALWAYS turn off the REILs or approach lights?
Will 3 clicks sometimes turn off the runway lights, and if so, any way
to know this in advance?
3. Why not have an ability to turn them all off, runway lights
and approach/REILs?

Just trying to help save Uncle Sam some $

Stan