Fire safety, watchdog function on gt2560

[valdemar4eg]

Today I woke up to check the results of printing overnight. With a horror I have found again freezed printer (happened couple of times already randomly) with heaters on and burned plastic around nozzle. Also I have found a bit melted board connector of the bed. Therefore I decided to study if there is any safety features which can prevent fire in the end. Turned out there is topic dedicated and cases of fire caused by faulty of 3d printers (http://reprap.org/wiki/Safety).
However I have a questions:
Is it normal that printer gets stuck randomly?
Why do we have WATCHDOG function OFF in our default firmware for I3x?
Can we use ATX power supply connected to mainboard to organize failure power off?
Do you use fireproof insulation for heating bad?
Which other passive and active fire safety features do you use?