The Gemorah in Brachas 54B, about 30 lines from the top, says that on seeing the pillar of salt that Lot's wife turned into, one makes the Bracha "Baruch...Dayan Emes".

First question that I have is, why is this the Bracha that was chosen for Lot's wife? Don't we say this bracha when we hear bad tidings the first time? This bracha that was chosen is to be said every thirty days at the minimum.

Second question is, do we actually know where the pillar of salt is?