Okay, even I couldn't stand looking at that picture of septic sewage/sludge anymore, so - taking pity on you readers who are still bravely and boldly hanging on - I will do a quick continuation of the story before I pop off to bed. It is a "school night", after all.
So, #2 Septic Guy had come on Valentine's Day and cleared out the frozen septic line. All systems were go. And, it was just in time for the plumber to test the master bathroom toilet he'd installed and the master bathroom tub and shower.
The toilet flushed just exactly like it was supposed to, and the water ran in the tub.
Unfortunately (see next posted picture) . . . .