Train assistance - point to point? Some kind of pass? 6 weeks

No need for a rail pass in Italy, many of your trains are regional and can just be bought on day of or use the app.
There are no discounts for regional trains- and they can't sell out. If you purchase tix at the station be sure to validate.
You can certainly buy and print all your tickets at home in advance if you don't want to deal with it there and like a paper copy (I do)

Book fast trains early for discount

https://www.trenitalia.com/content/tcom/en.html
Download the easy to use app as well and set up account at Trenitalia

Naples to Paestum. 4/23 regional

Paestum to Ravello. 4/25-NO train to Ravello- take train to Salerno then transfer to bus, ferry, cab or hired driver

Ravello to Florence. 4/28- reverse to Salerno then fast train to Florence

Florence to Bologna 5/1 fast train

Bologna to Bolzano. 5/5 fast train (some change in Verona)

Bolzano to Trento. 5/7 regional

Trento to Milan. 5/8 regional/fast- change in Verona

Milan to Turin. 5/11 fast train

Turin to Bellagio. 5/14 NO train in Bellagio fast train back to Milan, regional to Varenna then ferry or car to Bellagio

Be sure to use the Italian station names
Napoli Centrale
Firenze SM Novella
Bologna Centrale
Bolzano Bozen
Milano Centrale
Torino

Lots of info here:
https://www.seat61.com/train-travel-in-italy.htm

Christine has you covered in advice for Italy.

In Switzerland, you may find a 4 day Berner Oberland Regional Pass makes more sense, in conjunction with a Half Fare Card. The BO Pass covers almost all transportation from Lucern to Mürren and your time there including part of your return to Zurich. The BO Pass covers lifts, trains, buses, and ships but there is an up charge for the Jungfraujoch and Schilthorn. I believe your trip on the Bernina Express plus the discount on the BO Pass will make the Half Fare Card very worthwhile.

4/23 Naples (Napoli Centrale station) to Paestum - direct train.
4/25 Paestum to Ravello - no train goes to Ravello so you’ll have to take a train to Salerno and a bus to Ravello.
4/28 Ravello to Florence – direct bus to Salerno then a direct train to Florence’s SM Novella station.
5/1 Florence’s SM Novella station to Bologna - direct train.
5/5 Central Bologna station to Bolzano – direct train.
5/7 Bolzano to Trento – direct train but not sure if this route is covered by a rail pass.
5/8 Trento to Milan (Milano Centrale station) – direct train but not sure if this route is covered by a rail pass.
Turin and Bellagio should be day trips from Milan’s central station. There are direct trains to Turin’s Porta Nuova station and Varenna’-Esino station then ride the ferry to Bellagio.
5/17 Milano Centrale to Chur – requires a train transfer.
5/18 Chur to Luzern – train requires a connection.
5/20 Luzern to Mürren - train requires a connection in Lauterbrunnen; bus to Mürren.
5/24 Mürren to Zurich – bus to Lauterbrunnen then train to Zurich that requires a transfer.

Thank you everyone. Great information!