How does temperature and salary affect deep water currents?

Did you mean salinity? if so i think differences in the density of water can also cause currents to form and move. Density is affected by temperature and salinity. Cold water or water with dissolved salts (higher salinity) is denser than warm water or water without dissolved salts (low or no salinity).

Yes it can cause that

The answer is to reassure the reader about dangers of mad cow disease.