DIY CO2 system - is this do-able?

Greetings,
I'm planning a homemade CO2 system - I'm after a well regulated bubble rate.
At first I thought maybe I'd put a pressure regulator with just the 2 liter
pop bottle setup, but I assume backpressure could make the bottle explode.
So what I'm looking to do now is to get a pressure cooker with automatic
pressure release valve and integrated pressure guage (so far the "all
american" brand looks good - no rubber seal, built in gauge and pressure
release features.) Then on the lid I'd fit maybe an extra manual blow off
valve, solenoid and pressure regulator. (after that the regular diffusing
type stuff) I believe these types of cookers release at 15psi.

So I have two questions:
1. Would a solenoid be needed at all? My intent was to have it on the same
timer as the lights such that CO2 wasn't trickling at night. Should a guy
do this? If CO2 should enter constantly then the solenoid wouldn't be
needed at all and I could save a few bucks. (or maybe I should use it
without a timer for power failures anyways???)
2. How would the yeast/sugar reaction behave in a pressurized environment?
Will the yeast continue respiration under such conditions? (please say yes
:P)

Or am I completely on crack here? My hypothesis was that a bigger
yeast/sugar mix could be used, used more efficiently, and could increase the
time between yeast mixings... high pressure without the CO2 tank refills.

TIA




Andy