I just read through your posts. Quite a journey. Just want to address a couple things. The more live plants you have, the faster the tank will cycle and it will tend to be more stable.
You can do a lot with low light plants. Anubias, mosses and Java Fern can be tied to driftwood or rocks. They don't like to be "planted".
You can sterilize new plants. You can Google it. A brief Bleach bath. Plus rinsing for snail eggs. Diseases no. Algae or Snails are possible. But plants compete with Algae.
Also there are cool snails out there. And a majority do not eat healthy plants. I have Nerites
They aren't the easiest, but I had to try them. Algae eating machines !!!
Also I did not see it addressed, you asked about Pictus Cats. They will gladly eat any and all fish that fit into their mouths !! All Guppies for sure.
This is my low tech Non CO2
tank. I add plant food once a week. I will be putting root tabs in which will last months.
I would also recommend The Planted Tank forum as well as Aquatic Plant Central. Good resources. You might also see if there is a local aquarium or planted tank society local to you. Mine has been super nice. I've gotten free plants and shrimp and plan to give back now that my shrimp are breeding.
If you haven't already I'd lower the temp to 78f. Over 80 is too high for most fish AND the water holds less oxygen.
GL. I envy you your large tank. My largest are 10g for now.