Your plans, including the cruise outing, do not account for the poor physical infrastructure in much of this area. You were asked about Month Of The Year because the ferries don't run to all towns all year. But if your trip is in peak summer, that is also peak passenger load for every transit mode, and every sidewalk on the AC. If you have advance-purchase discount train tickets, you have to worry about ferry delays or omitted runs. This is not the simple plan you may think it is. And it's a lot of travel time for a short visit to one or two towns.
Another issue is that you have to change busses in Amalfi if you are somehow stuck with the bus.
You may wish to make up a day's schedule for yourself, after checking the Trenitalia site, and this year's ferry schedule, and then evaluate your risk of getting stranded by a transport irregularity, or vehicle that is too full to get on. (That happens in Sorrento and Positano all the time, not so much in Salerno.)