Hi Deepak -
Some questions and some partial answers -
When will the travel be occurring? What dates? It influences some possible travel arrangements.
1.- What is a travel card?
This link explains how to buy a Swiss Travel Pass and gives various details and options.:
If the group you have in mind is large, the process of buying it at a station can consume quite a bit of time.
Swiss Francs ( CHF) can certainly be used in Switzerland. ;-)
2- To understand travel times, please use the timetable:
The first page at that link has useful information that will help you use it better.
The fastest route is the default mode for the timetable.
In mid-October, beginning at 0642 there are two journeys per hour departing at XX12 and XX42, taking 5 hours and 10 minutes. They go via Bern and have 4 or 5 changes of trains.
The earliest journey starts at 0453, takes 5 hours and 29 minutes and includes a change of trains at Lausanne.
3.- Depends on when you plan to travel.
4.- There are dozens or hundreds of possible alternatives throughout Switzerland that can be reached in 5+ hours. What are their interests?
In addition to Luzern, two regions that come to mind are the Lake Geneva Region and the Jungfrau region:
5.- Reservations are not needed on intercity trains in Switzerland.
6.- please see the link to the Golden Pass route that Arno gave you in his post.
The Golden Pass is a route, and some trains have special panoramic cars. Regular trains also travel on the same tracks.
The Golden Pass route has a few sections. In some cases, alternate routes that take main line tracks are significantly faster ways to reach the destinations, but, are less scenic. Use the time table, making sure to insert a "via" station on the the route you choose, otherwise, you'll get the fastest route. Between Montreux and Interlaken Ost, the appropriate "via" is Zweisimmen. Between IO and Luzern, it is Meiringen or Giswil.
The fastest route from Geneva to Luzern bypasses the golden pass route and goes via Bern and Zofingen or Olten on high speed tracks.