I should remind you that I'm looking at three factors. Effectively when the reactor is on in relation to a window of run capability (heat), how much /power/ it produces as a result, and how much /fuel/ is used to obtain that (is any wasted 'starting' it up)?
a) what the startup delay between redstone off and reactor is (or if it simply checks once per second at a specific offset).
b) How many cycles of thermal rise are associated with the pulse of 'off' including regions during which no power is consumed.
c) If any fuel is used during the non-power production time periods.
I'll help you simplify, everything a reactor does, it does once per second. [So the second answer for A]
for B if you mean reactor pulse when you say pulse, the answer would be 1. (as it "gains" heat once per second, regardless of if the power is being used or not, as long as the reactor is on an running, it is producing heat as well as power.)
C) No. If the reactor is off (powered with redstone) it will use no fuel(uranium), produce no heat (unless you have more passive heating then cooling --- which is usually not the case so the reactor will usually cool based on it's cooling), and produce no power.
[[Sorry I just peeked again and... the reactor "updates" once per second, but produces power based on the last update tick for the next 20 ticks. (since it produces EU/t not EU/s :P) so if it was running and then was supplied with redstone power, it will continue to produce power until the next reactor pulse, when it will stop producing power and not produce power for the rest of that second. So theoretically you could waste almost a second's worth of power if the MFSU were just below full with that setup.]]