those sockets aren’t bad, i use to use them for cfl builds of the past, cheap and they work. you could just mount them to a 1x2 frame and wire them out to a single cord.
As for the voltages and amperage, that was what i had measured, the stuff on the boards as far as im aware are more parts codes and such not wattages voltages or ratings
As for the one power board, well yes up to a couple but like i said your reducing the power by half (2 lights) then a third (three lights) but your overall wattage will still be the same “14w” so the only reason you would do so is if your wanting to spread out the light over a couple COB’s and or wanting to increase the efficiency slightly, in the end though your will just have the same amount of light that is coming out of a single bulb say split to three instead. Also getting a separate ballast to say power them all is gonna cost you more that what sockets and a couple more bulbs will cost. But in the case of spreading out the light, the smaller 8w bulbs are actually cheaper to buy even at 2x compared to a 14w at least for me.
Really there is no point in doing so, i have but definitely not needed and more expensive.
As for a micro grow, just pick up a small propagation tent you can find them in the 2x2x4 to 2x3x3 range, anything else would be custom built, aka ikea cabinets, old repurposed cabinets, pc cases ect. But the tents can be found for $40-100
As for the least amount of power so far 10w ina 1 gal protein container, fan included lol, sqft wise lowest amount i don’t actually know as im usually on the higher end of things with how i build and grow, but that 35-50w is a very safe area.
Also head over to @Kingaizen69 thread https://overgrow.com/t/low-watt-growing/11046 just for some inspiration, his first grow in years too 