I'm new to ac and have a great deal of respect for it so I would like to iron out a few questions I had before continuing:

1. If I understand theory correctly, under no-load I should expect to see 120*sqrt(2) = ~170VDC. Under load, I understand this value will drop by a certain amount. Is there an equation that would help me identify what drop I would expect to see with say.. a 0.5A load vs a 1A load?

Additionally, is there a point where this drop "stops" per-se? I've read something about calculating under-load values with the equation VDC = (2*[VAC peak])/pi and am trying to figure out where this comes into play.

2. Is there a common way to to apply a load or drop the voltage so for a moderate range of loads, the voltage will remain somewhat steady?

3. What can be done to save the circuit in the event of a power surge?

I have a headache from reading about this all day, but at least I feel somewhat accomplished now.