DE is a good option. Iso usually works well too. I'd imagine after your iso spray you knocked most of them out. I'd spray them with neem in a couple days as a preventative and then just keep an eye on things.
I'd go LED. LED drivers let you dial in light intensity. I'd also go with a bar style light for the spread and penetration. I use a umol Technology light from Alibaba. It was a little over $700 shipped US.
I dechlorinate because I use benefices to keep root rot away and find with benes that my media's PH never drifts. I can just up my benes to compensate for the chlorine.
I like rockwool, but it's pricey. Too bad Great White isn't available. Worm Castings should be readily available and you can brew a tea with that for your beneficial. Here's a good thread on how to fight root rot/slime with beneficals...
Switching from the every popular GH Flora Trio to the MaxiBloom/Grow to simplify things and save a couple bucks. Anyway looking the Maxi series, it lacks alot of the micro nutes contained in the Flora series. Is there a way to get those back or do I even need to worry about it? Medium is ~5...
You can survive PM, but it often comes back and requires constant vigilance. You can treat for PM up until week ~3 of flower, then you're best not to spray stuff on the plant. I've seen crops ruined with PM. I'd image most people would start over and sterilize the environment/equipment.