the higher purity would be more suitable (the lower purity is for high pitched voices and balloon blowing, the higher purity even keeps balloons floating for longer!)
1) This is if CO2 builds up, eg if air isn't allowed to flow out
2) ooo, didn't think of that... tho u can test it by putting a glass of water near the outlet tube (once setup, not in the water but on the side of the glass), and seeing if it freezes (it shouldn't), there are also regulators for reducing pressure to 15lpm
3) don't worry, I can read and understand the message, maybe
https://pdfcoffee.com/qdownload/five-last-acts-the-exit-path-2015-2-pdf-free.html has helium guides
4) there are partner threads tho I'd be cautious about them.
5) dw, all good, I have wished for that peaceful rest sometimes.
Also, keep in mind that on here there is no requirement whether a person chooses life, death, or other options.