Just a quick addition: you cannot activate a new e-gate card at the immigration office after immigration at the FC/BC departure clearance area. I wanted to do a new activation on my new Gold card there, queued for about 20 minutes, and on reaching the officer at the e-gate desk I was told that they could only do renewals there - no new activations. This although I was told by the Emirates agent at checkin that I could activate my Gold card there.