I find the need to A) Put a better headphone jack in my genny and B) add headphone jacks to some of my systems. Can i use the auido L/R signals from the video port?
Yes, however, the fixed audio output on most systems you will find is not very loud. One solution to this is to put an audio amp in your system. My saturn has an audio amp in it with a headphone jack.
ok is this something that i can pick up at radioshack and won't put a dent in my very low budget?
I recommend using amplified computer speakers. Many amplified computer speakers have headphone jacks on them. You could scrap them to get the amp, jack, volume control knob, etc. Even the ones that don't, if they have an amplifier, you should be able to get them to work fine with headphones. Just don't turn the volume up so much.
As far as Genesis, the headphone jack on the Gen 1 is really nasty, but I came up with a fix for it (in another thread not far down the list). You could use the fix, and then use your own headphone amp for somewhat better sound. It will still suck, though, just not by as much. CDX and Nomad are the only way to get decent sound. Perhaps a Gen 3, I don't know.