Interesting about the feedback from humming, I've kind of had a similar thing with the whistle at events - ie, if I *can't play* (and it's not just that I've been doing something active), then I know damn well I need to sit for a few minutes and wind down.

I have a massive preference for colours with light behind them, like the sky, personally; those are the things I can just staaare at.

(re: breathing 3/5 and struggling to exhale enough - the tools I'm familiar with suggest a 1:2 inhale:exhale ratio, which might suit you better? Me, I struggle with 1:2 for the opposite reason; too long an exhale.)