Not addressing everything but in regard to pill testing, there are policies in place. When it was carried out at a festival earlier in the year they had full anonymity policies in place that protected both parties, but people were still arrested if they were caught bringing drugs into the festival.
And to use your analogy, it's like playing Russian Roulette. Pill testing just removed the bullets. How can that be a bad thing?
Pill testing in my analogy, the bullet is unremovable (it's the pill), hence it would simply say "you'll fire a bullet but it just may not kill you".
Also keep in mind many people will be popping them before entering the establishment, whilst others will hit trouble when booze (and whatever else they've taken or are on) combines with the ingredients of said pill.
So pill could test as "fine", but when combined with nangs, or cocaine, or alcohol, or pseudo, or even dehydration, or meds they are on for something else, could create a deadly reaction.
There really isn't any solution to allow the safe use of drugs, testing or otherwise, because variables are far too great.
What the advocates fail to highlight is overseas deaths have still occurred even with testing, but it doesn't fit the narative they are driving. Reduced or otherwise, I'd say the number of pill related deaths a year is currently acceptable without society changing to accommodate junkies.
The other option is simply to NOT TAKE DRUGS and have 0% risk. If that message isn't clear enough let the bodies pile up.
Less burden on the health care system in the long run.