I have a 2001 Honda Civic and need to drain and fill my radiator. I
have read some tutorials but have a few questions:

1) Some have advised draining the radiator, then filling with
distilled water and running for a while, then draining the water and
filling with coolant. However, if I put water in, won't that get
circulated into the engine block? If so, when I refill the radiator
with my pre-mixed 50/50 coolant (comes this way from Honda), then my
coolant in the system will be super diluted as it mixes with the water
I introduced into the engine block. Am I missing something here?

2) If the car has a bleeder valve (not sure if it does, I'll have to
check), how does it work? Do I simply open the valve while filling the
radiator while the car is off? Or do I fill the radiator, close the
radiator cap, then open the valve while the engine is running?

3) If I do the bleeding method where I open the cap and run the
engine, do I simply observe the fluid in the radiator while the engine
is heating up, and pour coolant in as the level drops, WHILE THE
ENGINE IS RUNNING? At what point do I need to worry that the coolant
will get so hot that steam blows my head off? Or does this not happen
since I'm running the engine with the cap off, preventing a pressure
buildup?