It could be, but the movie rumour was debunked as hoax a week or so ago so I'm afraid it won't be happening. :/
As for the poisoning, yeah, just like the name implies it's literally referring to a poisoning, as in "a bunch of people got poisoned and died". Chances are the DOD got notified of the deaths just like any other via the tube system (remember, Manny had to 'steal' Meche's notification), but because the amount of deaths was so great Don decided to just let the reapers take whoever they could find.
If I remember correctly, he says "first come, first serve" in the memo, which of course means "if you get there before everyone else, you get to reap that soul".