Point No. 1 has proven itself over time in various places. It seems that seeing their "work" painted over in less than a day takes most of the fun out of it for the vandals. Also, I believe some progress has been made in developing vandal-resistant surfaces making graffiti removal much easier.
In Philadelphia, PATCO thoughtfully placed its shops just beyond the endpoint at Lindenwold. At the end of each run the operator walked the empty train, and if there were any slashed seats or graffiti the trainset was immediately taken out of service and replaced by a "protect" set which was ready and waiting; the vandalized train was not returned to service until made presentable. The first General Manager gave a presentation before the Philadelphia Chapter NRHS at a time when graffiti were everywhere on the Broad Street Subway, and when asked how come PATCO had no graffiti, he smiled gently and said, "we don't allow it." PATCO also went after fare jumpers from the beginning; they were arrested and booked, and afaik fare jumping never developed into a serious problem.
