Hello SwissRetreatbyBee
It is valid for 10 days, however it is not a 10-day travel pass. You can travel the selected route one time within 10 days.
Group tickets for long distance journeys do come with unsolicited seat reservations.
For that purpose you have to communicate your itinerary. It might be that a connection you would like to take as a group is not available due to other groups and related capacity restrictions. When booking group tickets, you benefit from a discount. In return, you have to communicate your itinerary to allow public transport companies to plan their rolling stock, or to propose you an alternate routing, to assure there are enough seats available.
If you want to travel independantly, you can simply purchase individual tickets at regular cost, without seat reservations, but taking the risk that the transportation of all group members might not be guaranteed, or only in batches of a few people.
Kind regards,
Roland