You would need to configure a M143 heater protection instance to trigger a power shutdown. Something like this:
M143 H1 P1 S300 A3 ; Set heater 1 monitor 1 to trigger printer shutdown if temp exceeds 300C
see https://duet3d.dozuki.com/Wiki/Gcode#Section_M143_in_RRF_3_01RC2_and_later
In the M92 command, the Y parameter is the steps per degree of rotation of the turntable.
When you give a G1 H1 or G1 H2 command (or G1 S1/G1 S2 for older firmware versions), the Y coordinate in that command must be specified in degrees.
I have found that this calculator can be illuminating: https://www.thinksrs.com/downloads/programs/therm calc/ntccalibrator/ntccalculator.html
Crydom and Schneider Electric are both reliable brands. I would add that amazon has a big counterfeit product problem as well.
For the reciprocal I am using dot '.' as a decimal separator. Since you use comma decimal separator ',' you'll need to put that in instead.
So the corrected one for you will be 1/2,3399e-4
Regarding the slight difference in output, it's likely just due to the precision of the calculations on the computer.
The bit about the 1/B and β being equal is not of real practical use but I find it interesting 
Trigger 1 is already reserved for a print pause trigger, so you could try renaming your file to trigger2.g and reconfiguring the trigger to use T2.
If you are calling other macro files with M98 command, I think it will only look in the /sys/ folder. To get around this, you could move all your macros to /sys/, or use the full path like so in your script: M98 P"0:/macros/mymacro.g"
SRS calc is this:
C =((1/T1-1/T2)-(Math.log(R1)- Math.log(R2))*(1/T1-1/T3)/(Math.log(R1)-Math.log(R3)))/((Math.pow(Math.log(R1),3)-Math.pow(Math.log(R2),3)) - (Math.log(R1)-Math.log(R2))*(Math.pow(Math.log(R1),3)-Math.pow(Math.log(R3),3))/(Math.log(R1)-Math.log(R3)));
B =((1/T1-1/T2)-C*(Math.pow(Math.log(R1),3)-Math.pow(Math.log(R2),3)))/(Math.log(R1)-Math.log(R2));
A = 1/T1-C*(Math.log(R1))*(Math.log(R1))*(Math.log(R1))-B*Math.log(R1);
Is it possible the emergency stop command is resetting the buzzer output signal as well?
To test this, you could try to insert a delay before the emergency stop to see if the buzzer works (for a short time) and then stops, something like:
M42 P5 S1 ; activate buzzer
G4 S5 ; wait 5 seconds
M400 ; wait for buffered commands to execute (maybe does nothing?)
M112 ; e-stop