Yes. Drama can be studied continuously in all years from Year 8 to 12.
A full year of Drama in Years 8 and 9 is an excellent foundation to build on for Year 12, even though it seems a long way in the future. As long as you also complete a full year of Drama in Year 10 and at least one semester of Drama in Year 11 (preferably the whole year), too, you should be fine in Year 12.
Yes, it is absolutely compulsory that all Drama students attend. We rehearse our productions in less than half the time that other schools do, so these out of hours rehearsals are crucial to ensuring the production comes together with the speed that it does.
No more than any other subject, but we do include written work as like with all subjects, it is important for Drama students to understand the history and theory of theatre.
No more or less work, as long as you are organised.
Drama at Westminster starts developing understanding and performance skills using four internationally recognised theories from Year 8 onwards. We also rehearse productions in half the time that other schools do, which is an intense, real-world learning process.