poolpop - Thanks for addressing that! It does appear that the sand was getting in there while the multi port valve was broken. Since replacing it and getting the Polaris going, the Polaris seems to be picking it up and I don't see more getting into the pool.
For everyone, an update:
It appears my FC held overnight. It was 25 when I went to bed, and when I got up - about 90 minutes after sunrise - it was at 24. I put a little more bleach in this morning, and am going to keep it shocked the rest of the day, but I think I am in the home stretch. The water in the shallow end is sparkling, and in the deep end I can clearly see the drain (so much so that I was able to find a screw I dropped yesterday while replacing the lamp in the light)...though the water is not quite as "sparkly" as the shallow end (another reason to keep the shock going for the day).
Also, I have already burned through my FC reagent, so I'm going to be ordering some more of that tomorrow. I can't find a pool store locally that sells Taylor reagents, so it looks like I have to order it online. In the mean time, I did buy some of the strips from my local pool store...though they only measure FC up to 10, so that doesn't help me a ton at the moment.
Any final words of advice on getting this thing going for next Saturday? I have had an amazingly productive last 3 days, in part because of all the great advice I have received from the site. Thanks again to everyone!
Attached is a photo just taken of the pool. It is starting to be beautiful!