Most antifreeze will work in any engine. For diesel engines in general, use a good long life coolant that includes nitrates (red stuff). For regular (green) coolant, most diesel manufactures require you to add your own nitrates or DFCA to this mix to prevent pitting of the cylinder liners. Check with your engine manufacturer for specifics.
It should not be.
Compression
Yes, you can change the engine of a Toyota used car from diesel to petrol or LPG Gas. Some D2 engines are used in late models already have diesel engines.
Diesel engines use propane to go faster, only gas engines use NOS
No. There are carbureted diesel engines, but they're mostly used in models.
Diesel does not require a spark to combust.
Diesel fuel cannot be used to produce gasohol as gasohol is a blend of gasoline and ethanol. Diesel fuel is used in diesel engines while gasohol is typically used in gasoline engines. Mixing diesel fuel with ethanol to produce gasohol would not be compatible for engine operation.
Size, weight, drivability.
Of an individual diesel engine and an individual steam engine of the same energy output the diesel engine would be less polluting. It is far more efficient. However, there are far more diesel engines than steam engines in the world today so overall diesel engines pollute more than steam engines.
A standard 20 to 1 otto cycle is used for the petrol and diesel cycles for diesel engines. It is higher than gasoline engines due to the way diesels burn and compress fuel.
Yes, biofuel, like biodiesel, will run in diesel engines. Many ships have diesel engines run on fossil fuel diesel and they will easily run on biofuel.
two stroke diesel engine is used in cargo ships as cross head type engines, two stroke petrol engines used in two wheelers.