When a booking is created via Tally Workspace, is a user created as a drop-in on the OfficeRnD side? 

When using the integration with Tally Workspace all bookings are made under the 'company' named "Tally" on your Office Rnd account.

When a booking is created via Tally Workspace, is a user created as a drop-in on the OfficeRnD side? 

No, Tally Workspace does not create a user as a drop-in for each individual booking.  Instead, each booking is made under the  'company' named "Tally" on your Office Rnd account.  We do this to ensure venues have a clear audit trail of all of their Tally Workspace bookings. 

How do I know who will be attending each booking? 

In the details of the booking on your Office Rnd account, you will be able to see in the description the attendees.