0
They happened, but no immunosuppressants were available. So the transplants generally failed. Here's a timeline:
http://www.wellcomecollection.org/whats-on/events/in-or-out/transplant-timeline.aspx
unlcuky we do not know
Kidney transplants, followed by liver transplants, are most common.
Yes, heart transplants are commonly performed.
Transplants - band - was created in 1999.