People, this is not that hard...
Mag switches I have seen (Piper, Cessna etc) are, left to right: OFF RIGHT LEFT BOTH START. Therefore the description in the magazine is correct. LEFT mag selected means the LEFT mag is OPERATING, RIGHT mag EARTHED (ie not operating). Vice-versa. If there is NO DROP when we select a single mag, it usually means an earth wire is broken and we stay away from the prop for a while due LIVE MAG.
As for pretakeoff checks, it's not that hard to check mag position entering the runway as you hit the transponder/strobes etc. Check the oil T/Ps when you roll. I am happy to do the runups with the oil temp 'off the stop', but takeoff with it out of the green? No thanks! And if the RPM isn't somewhere in the green arc and close to the red radial, it's probably a good reason to stop.
Anyway, I'm off to read the article
P.S. a quick search turned up an old article from Flight Safety which describes typical ignition systems very well. It can be found
HERE 