Hello Kathleen, this seems like a good and easily achievable plan.
I can't help you from experience with the cruise ship to the train station part of your plan. I would check with your cruise line about maybe an transfer to the train station shuttle or option. If they don't provide that a cab is really probably the best option since the station isn't super close and bus service seems slow. Google maps works pretty well in northern Italy to check bus routes and schedules BTW. I'm sure those taxis would be happy to take you to Pisa or Florence but cost for that trip versus the price (>120e) of the train does not seem worth it to me but that's up to you.
Check the timing of the tickets here: https://www.trenitalia.com/en.html (use Firenze SMN for Florence) and look at similar timings o Saturday and Sunday since tickets for your visit are probably not listed yet.
The train takes 1:20 direct and there seem to be at least trains every hour sometimes more than one train an hour and cost about 11e. The trains don't have reserved seats so I wouldn't bother with buying tickets ahead of time but instead use the Trenitalia app to buy the next ticket when you know what time you will arrive at the station or use the kiosks at the station if you want a paper ticket and aren't pressed for time. Always validate your ticket in the machine at the train station or in the app if you have an e-ticket.
If you have only an overnight case I would consider your hotel to be walkable from the train station (850m ~11 minutes) since most tourism is Florence is just walking around, but you could also grab a cab from the train station if you are intimidated stepping off in the somewhat chaotic Florence train station.
I would reserve in the afternoon for Accademia since it is a faster faster visit and then as early as possible for the Uffizi on Sunday. The Duomo museum - directly behind the Duomo across the square - is great if you have time for it. The "big" shopping streets are adjacent to the Duomo area and the smaller, funkier shops tend to be across the river in the Oltrarno.
I would obviously leave enough time coming back to get back to ship if you need to wait for a taxi at the train station since many people will probably be coming back to port near the same time.
Hope that helps, have a great trip,
=Tod
