We currently already have a couple of bookings for the July departure of our solo South Africa tour. With regards to contacting other travellers beforehand it is possible, however due to data protection regulations people must give their consent before we pass on their contact details. But don't worry we have done this before.
With regards to your other questions the group, including the tour manager, always stay in the same hotels and travel together. Excursions are also done as a group (though they are not compulsory) and at times there is free time where you are able to choose your own programme (our tour managers will be more than happy to suggest options).