Hi, congrat's on the progress! Must be exciting. I'll bump your post so others will notice and come and help. I'll leave your questions to them, but here's a tip, in case you haven't heard of it before.
This might be the last time your pool is empty. Take advantage of this opportunity to fine-tune your pool's water volume number, as this only works when you start with an empty pool. You have to keep an eye on the plaster guys, because they'll probably start your fill the minute they're done, without letting you know. Just before they do, run out to the street and find your water meter. Take a picture of the numbers. You'll probably be the one that has to watch the pool to turn off the fill. When your water level gets halfway up the skimmer's opening (that's usually the ideal water level), turn off the water and then run back out to the meter and take another picture (day or night)! The difference between the two numbers will be your pool's actual water volume! Water company meters are usually accurate to 1% or so, so you'll have a very accurate number. Do the same thing for the spa. The two numbers together will be your total water volume (which you'll use for calculating chemical doses), and if you do the pool and spa separately, you'll have good numbers for each of them as well, in case you might need them someday.
You can improve the accuracy of the water volume numbers by limiting water use on your property while the fill is running. Turn off your irrigation system. Limit showers and flushes. Take the day off from dishes and laundry, etc. The less water you use in the house, the more accurate your volume numbers will be...