Variable DC
16V AC
12V DC

On another powerpack I have terminals for:

Track DC
Accessories DC

I know that the terminals for "Variable DC" and "Track DC" are for providing power to
track which is controlled by the rheostat and is therefore variable. It seems to me
that if I connect lighting to these terminals, I can vary the intensity of the
lighting. The terminals for "12V DC" and "Accessories DC" could also be used for
lighting but is a constant voltage. I think this is where I want to power my switches.

My questions are as follows:
1) What would I use the "16V AC" terminals
for?
2) By turning the rheostat and therefore controlling the output power, could
I use these terminals to power switches provided I have the rheostat turned up
to the maximum?
3) The lighting that I will be using is for panel lights to indicate switch position,
trackside lighting, and lighting within buildings. What kind of lighting should I
purchase? Should I buy 12V DC lights? Can 12V DC lights be used with the "16V AC" terminals?

Thanks,