It should be listed in the owner's manual.
It will vay depending on the model and when made.
if the gauge and chamber length are the same
@ 40" or so depending on LOP and Barrel length.
26"
They were made in 24". 26", 28" and 30"
A little over 36"
Should be marked on the barrel
Should be marked on the barrel
No way to answer without knowing barrel length and gauge.
While the original length is not indicated on the barrel, the barrel weight is. Example: 1Kg012 which would mean 1012 grams. An accurate scale would help you identify. If the barrel weighs less than the stamped number then the barrel has been altered.
You will have to provide the model, type of action, barrel length, gauge
You will need a gunsmith to assist with measuring.