Regarding the Pompeii portion, my sister and I went there last July and we did a self-tour (you can always listen to one of the tour guides who is with a big group, just mingle in and there isn't a problem), took the train from Rome to Naples and then the other train to Pompeii, we had about 3.5 hours in Pompeii, arrived there at around 1, had lunch there, and got back to Naples around 5:15, definitely better than taking the bus.