Do Twisted Nematic LCD need refresh (polarity reversal)?
All LCDs have to be driven with AC. When you use DC instead, you get a ghost image which fades away rapidly. The difference between TN and STN is the amount of twist each LC molecule does, nothing more.

You can have an active matrix with TN and STN, but TN has nearly died out, what's advertized as "TN panel" is STN in fact. For low-temperature applications, TN is better than STN and may be still available.