No. If you get into an accident, first responders are going to see the placards and assume the hazardous materials are loaded on the trailer. If you're in a state where you're unable to communicate with them, they're not going to be aware that there are hazardous materials in the cab of the power unit.
A store that sells a tractor cab is Sears. For example under the topics Lawn and Garden and Tractor attachments, listed is a Craftsman brand Tractor Cab.
semi cab
A conventional tractor is what much of the world outside of North America refers to as a "bonneted" or "hooded" tractor. It has a hood which extends out in front of the cab. This is in opposition to a COE (cab-over-engine) tractor, where there is no hood.
You can. There's a provision in the hazmat regulations that allows you to carry a small amount of hazardous material necessary for the operation of the truck without filling out a hazmat bill of lading for it. I wouldn't carry the cylinder in your sidebox, though; if it leaks the propane will go right into your cab. (You would need to provide a box for the cylinder. You are not actually allowed to carry ANYTHING on your catwalk per DOT regulation.)
Many hardware stores sell tractor snow cabs. One can purchase a tractor snow cab at Lowe's or Sears. The price range is usually around $200.00 US dollars.
300 pounds
yes
in the cab by the brake
You can identify a Massey Ferguson tractor because it has a red cab and bonnet and grey wheels.
day cab is a truck with no sleeper, just a standard cab
is it complete with frame?
Day cab or not, there'll be a primary air tank, and a secondary air tank.