The gold table I have can be found at www.royalmfgind.com . Click on prospecting, then go down to the second item, the gold dust concentrating table. They should have a video as well. That should answer all your questions. This is not the only type of equipment for fine gold recovery. Lots of other manufactures as well. You can still pan the material but do very small amounts and look it over good in the sun .
Sounds like you are on to something at that road cut. The best way to sample the quartz vein is to go across it from left to right a little beyond the vein on each side. It may not be easy to break out the rock. Quartz is very hard. Take some sample bags and record the areas. That way if you hit a sweet spot you know where to start digging.
Maybe others will chime in and give you some helpful tips. Let me know what you find.