Way too much to read through everything. Here's some of my experience with anxiety for what its worth.
Regarding caffeine and weed, if you have stress and anxiety issues (maybe your self-medicating with weed? I was), and constantly raised adrenaline and cortisol levels and you're getting panic attacks and constantly having negative thoughts, reducing or cutting out caffeine will probably help a lot, it did for me. I assume this is down to caffeine having an effect on sleep regulation and it can cause increased adrenaline and slightly increased cortisol response on its own anyway from what I've read. I found switching from coffee to tea helped, but had to quit for awhile too, it's just hard to stay off it permanently. Probably won't make a huge difference if you have a dreadful diet, take no exercise and don't look after yourself though. It really depends on what's causing your problems. Weed itself isn't for everyone after all, it can be too much of a head fuck for some people.
Logically though if you're adrenaline response has gotten wired to spark really easily, then even mild stimulants will trigger it, hence caffeine problems.
I think I made the mistake of trying to repress/reject negative thoughts for a long time which really just seems to make them worse, now I find discussing the fears as they arise with my unconscious/brain, which as stupid as it sounds, works. Still my problems were more related to drinking wayy too much coffee for way too long and compounding it with dodgy blended RCs and a couple of bad experiences and you find your own mind is trying to fuck you up
Rather than weed that is, only thing I found with weed is like I said above, it makes it too easy to dwell, almost leads you into your own mind and if it's full of jagged mirrors and daggers it won't be much fun. But if you're mind is good then weeds always been good with me. Unless I'm around other people, then I wouldn't toke, makes me horribly self-conscious. Probably need to talk to my brain about that.
Don't underestimate what a high caffeine intake can do though, especially if you're already worrying a lot or not sleeping well.