The Cuirassier regiment (it is unknown if they actually wore a cuirasse or not) was, as per Kronoskaf, a motley crew of 4 squadrons with contingents from 61 different places and totalled about 600 men under the command of Fürst Friedrich von Hohenzollern-Sigmaringen. At Rossbach they were routed by two squadrons of the Black Hussars.
The Sachsen-Gotha Dragoons (not to be confused with a dragoon regiment in the Austrian army with the same name!) was a small unit of about 250 men. It's reputation is unknown.
All figures are from Front Rank.