The answer looks to be YES to both concerns. The chemicals are used in cooking...and blowing up stuff. That is kind of cool by itself!
As a licorice lover, the fact that one of the chemicals, sal ammoniac, is used in the Nordic countries in a salty licorice candy opened a new world of treats to me. (And, yes, Amazon has that, too :-) You could kill yourself with the chemicals if you were really dumb or determined, but it seems highly unlikely. I found a 12 inch glass hydrometer test tube for sale that was the right shape to substitute for the fascinating bottle illustrated below. I wonder what that shape bottle was made for in 1870.
The only problem is the cost gets to about $50...so I am out. Sheesh...I wanted to see the star shaped precipitate rising and falling with the weather changes!!!! Time to start looking around for friends with a bit of this and that laying around...maybe someone cures meat with saltpetre. I have a tube already from aborted wine making...that gets it down to 40ish. I think I need to retire to have the time to pursue all this.
The last question is - does it work? No clue.