Hmm good question, I'm not sure. The pH of your soil could be too acidic (or alkaline) in order for calcium to be taken up by the plant. I think its a good call adding the calmag, hopefully it helps bring the pH up. (if that is the problem)
The main plant is fine, you just gave it a massive top haha! Just like the others said, put the piece that broke off inside a humidity dome. Keep them cells turgid boi
Yeah, I know exactly what you mean brother. Botrytis has ruined entire crops in the past...Ever heard of over mature/dead pistils being the cause of Botrytis, inside the dense buds?
I don't know of any fungicides that are safe to use on cannabis. I honestly would steer clear of chemicals and focus on cultural practices. Who knows what is in those chemicals and if you ingest them.
It might be spider mites! It's hard to see with the naked eye but if you look really close you can see little specs crawling around. I got this picture off of google, does it look anything like this?
Yeah it's really hard to tell. Can you post more pictures of the buds cracked open, with the mold showing? I don't know of any chemicals that are safe to use on cannabis, sorry!