Display MoreAgreed. This is a building game; building is good!
Toggle latch is probably a better way. My brain hurts trying to figure out logic gates. No idea how I passed that subject at university.
As to the Mass Fabricator idea... to ensure your mass fab doesn't consume any power until your workshop batteries are full, you could put a splitter cable inline with the cable that feeds the massfab and use the MFSU full signal (and an inverter probably) to allow excess current to flow to the massfab.
As to building complex things, definitely a lot of fun. Problem I've found though is that playing on SMP, even though I host the server on my LAN, things break more than I suspect they do in SSP. E.g. I made a bucket CARUC with rp2 deployers and filters. It worked just fine for an hour or two when I was online but I logged, slept and logged back in to a crater
So sometimes complexity can be a bad thing
and thats why i never use an casuc on an server 
you should try an ice CASUC with some nifty piping.
with nifty i mean - logistics pipe's with item detector pipes in between.
that saved my house an couple of times, (or at least my bomb proof room)
its not that hard, CASUC on an server, but it takes alot of (how do you call it on server? memory? :P) and is suspectible to lags.
log pipes overcomes that, i started using that system after i accidently blew up the spawn of the word 
(half the base was suddenly gone hahaha)
but i might start working on mass fabrication using that thou, sounds like alota fun to construct an system like that.