Hello Ron Sherf
Welcome to the SBB Community.
1.)
To book group tickets online, you need an SBB account (sbb.ch > Login).
But even then, certain trains are not bookable for groups since their booking is not allowed, or due to lack of space, or other reason. Therefore, it might be necessary to still call the SBB Contact Center. And, from experience, this is still the easiest way to book the tickets.
2.
The minimum number of travellers to grant the group discount is ten. If you book a ticket for ten people while ultimately a fewer number of people will travel, you will not get a refund for the none-used tickets.
Kind regards,
Roland