Hi Swiss>3,
You can plan this using Google Maps and the SBB timetable. When you see where places are in relation to each other, you can group them together and plan the order in which to do them. The SBB timetable will show you how to get there and how long it will take.
Attractions that have opening hours will display their hours on their website, so take that into account as well.
Once you have found the attraction you are interested in on Google Maps, look for a nearby railway station, bus stop or boat dock. Google Maps shows bus stops, railway stations and boat docks (as well as cable car stations etc), including the official name for the stop, which you can then use in the SBB timetable to plan a route there. When you see the symbol for a bus stop on Google Maps, hover over it with the mouse (if using a desktop computer), or tap it (if using a hand-held device) to see the official name of the stop. Many attractions will also provide information on their website about how to get there.
When you mention “Watch Valley”, what did you have in mind specifically? The Swiss watchmaking industry is largely centred around La Chaux-de-Fonds and Le Locle, located roughly 2.0-2.5 hours by train from Montreux. You can check the location of those cities on Google Maps.
Gruyères is a small village. You can find restaurant options here:
https://www.myswitzerland.com/en-us/experiences/food-wine/restaurant-choice-search/-/gruyeres-1/
Regarding the Lavaux, please see these threads:
https://www.myswissalps.com/community/thread/lavaux-wine-area-self-guided-tour/#post-956211
https://www.myswissalps.com/community/thread/comments-on-our-detailed-17-day-itinerary-in-sep/#post-1342952
https://www.myswissalps.com/community/thread/montreux-to-lavaux-vineyards/#post-1436685
Here are some typically Swiss restaurants in Geneva:
https://www.myswitzerland.com/en-au/experiences/food-wine/restaurant-choice-search/-/geneva-region/?gastrobestof=typicallyswiss
Use the SBB timetable to find times for boats from Montreux to Vevey.
I don’t think you will be able to cover everything on your list in 2 days, so you might need to prioritise. I would suggest you go to Chillon Castle on your arrival day, visit Vevey and the Lavaux on another day, and go to Gruyères the other day. I would skip Geneva in view of the limited time you have available.
Hope this helps!
Alpenrose