2)The characteristics of Roman theatres are similar to those of the earlier Greek theatres, on which they are based. Much of the architectural influence on the Romans came from the Greeks, and theatre structural design was no different from other buildings. However, Roman theatres have specific differences, such as being built upon their own foundations instead of earthen works or a hillside and being completely enclosed on all sides. Roman theatres derive their basic design from the Theatre of Pompey, the first permanent Roman theatre.http://en.wikipedia.org/wiki/Roman_theat...
3)Although the Romans thoroughly enjoyed the Latin versions of Greek drama that were performed in Rome, the authorities were concerned that the Roman people might be corrupted by Greek influences. As a compromise, drama continued to presented at various religious festivals, but the theaters were all temporary structures, put up just before the peformances and taken down afterwards.
The Roman theater, although similar in form to the Greek theater, developed a magnificence and splendor in keeping with Rome's imperial status. This grandeur is most evident in the stage building, which was raised to the height of the seating area. Thus the stage building was normally three stories high in comparison with the two stories of the skene in later Greek theaters