I think it might be a good idea for you to observe some interpreters and Deaf students in a classroom setting. Then you can see for yourself what goes on. Of course, this is the wrong time of year for that but maybe you can use this summer for finding out where the Deaf students and terps are located in your area.
Yes, terps usually go to every class that has a Deaf or HoH student.
There are as many or as few Deaf/Hoh students in each class that attend the school at any given time. Sometimes there's one, sometimes several. It just depends on what the Deaf/Hoh student population is, and which courses they are taking.
