Whatever the speed limit for any other vehicle on that roadway is. Most of the Interstate there has a 75 MPH speed limit (except when going through cities), and you're allowed to drive 75 (provided your truck isn't governed below that).
The same as it is for any other vehicle. Montana does not have a separate commercial vehicle speed limit, save for mountainous areas of downgrades where vehicle over 26,000 lbs. GVWR will have a lower speed limit indicated in signage.
Do not exceed the speed limit is correct
In practice, It is acceptable to increase the speed of your vehicle over the legal speed limit to pass or overtake another vehicle. Legally, it is not permitted. If the other vehicle is already at the speed limit, you should not be passing it. If it were a police car you were passing, at any speed above the speed limit, they could stop you.
The speed limit is exactly that - the speed limit. While a reasonable excess of speed might be overlooked when overtaking another vehicle, there is no guarantee. You can be pulled over and cited for speeding, still.
Depending on what you damaged and what the vehicle is, you could cause 20K damage to a commercial vehicle at idle speed.
Yes it is acceptable to momentarily accelerate over the speed limit tp get around a vehicle moving slower than the posted speed limit but you must return to the speed limit after passing.
There currently is not.
The posted speed limit.
All vehicles get the speed limit on the road, whether it is a motorcycle motorbike or whatever, it it is a vehicle it has a speed limit.
Most states don't have truck speed limits. So in a state like Colorado, New Mexico, Arizona, etc. (where the speed limit is 75), trucks can do the speed limit.
Add a governor to limit the speed of the engine or vehicle.
In practice, It is acceptable to increase the speed of your vehicle over the legal speed limit to pass or overtake another vehicle. Legally, it is not permitted. If the other vehicle is already at the speed limit, you should not be passing it. If it were a police car you were passing, at any speed above the speed limit, they could stop you.