I appreciate all the good advice, and the
paint-thread reference and the clarification of why the pool paint exists as a thing, and that it won't last long, and that it might even make some things worse. This is all GREAT information, as that means, for sure,
I'm not gonna even think further of painting the pool (as I don't really care what it looks like).
As for getting water into the pool, that will be started tomorrow - as I had pumped it out a couple days ago and then I brushed the sides as much as I had the strength to do.
I ordered a few 10-pound bags of CYA and 50-pound bags of calcium salt which are scheduled to arrive tomorrow (as I know the well water chemistry is about 135ppm).
I have seemingly almost infinite sunlight so I'll keep the CYA in the higher range most likely around 30ppm or so - and I never use tablets or powdered shocks; so it should stay wherever I put it (excepting for evaporation - as there is no rain until the California monsoon season).
I'll take a trip to the local HASA supply house to get a few cases of liquid chlorine & hydrochloric acid as it takes a while to balance (as it takes far more acid to balance, even when done super slowly, than I'd like given HCl is not only expensive but acid doesn't directly help with sanitation).
Unfortunately, in my ignorance, I had experimented with borate with the prior fill - so all the water had to go; but it's easy to fill in terms of garden-hose effort - although it will take about a month (or even two), elapsed time - since the well water sporadic flow rate is limited in volume to somewhere between five hundred to a thousand (at most) gallons per day (these flow rates fluctuate year to year so they're only rough estimates).
Much appreciated the kind & helpful advice. I love advice which enables me to make a clear decision that I don't need to worry about afterward.