I would recommend visiting Paris first and not at the end. You'll be exhausted after your flight and it's not a good idea to visit elsewhere right away.
Some advice about reservations :
They are mandatory between Paris and London + London and Lille or Brussels for Bruges (30€ extra). It's a popular route and there's a passholder quota so book in advance. Check availability on https://www.b-europe.com/EN/Booking/Pass#TravelWish
Reservations not possible (nor needed) in Belgium and the Netherlands as long as you avoid Eurostar to Amsterdam.
Between Amsterdam and Lucerne consider the good night train to Basel (early arrival)/Zurich. There are private compartments available if you book long enough in advance. With a pass you only pay accommodation fare.
It's also possible to do the journey by daytime trains but it would take most of your day.
Reservations aren't a thing in Switzerland : you simply log the train on the app and hop on.
Special case : 49 CHF mandatory reservation on the Glacier Express. Also possible to do the same route on reservation-free regional trains on the same route -> less crowded, pull-down windows for part of the journey :)
Unless you have a reason to visit the city Geneva isn't worth your limited time in my opinion. Add a night in London if it's your first time.
Geneva - Paris : 29€ mandatory reservation for the direct TGV. Can get down to 10€ if you cross the border on a regional train before hopping on the TGV.
With all that being said I'd get a 15 days within 2 months pass to include all your day trips. The price difference with a 10 day one isn't that big and then you don't have to worry about tickets for small journeys. 1st class also doesn't cost much more so consider it ! There's a 25% sale going on but passes must be activated on 1st June at the latest.
Further questions welcome.
