1. if you have cash, yes.
2. yes.
3. don“t think there is any difference in speed between the three.
4. Mediator (see Elbox website)
5. only Mediator is still being produced and for G-Rex you did need a PPC turboboard to connect it to.
Both Prometheus and Mediator could connect to a standard A4000 and Mediator can also connect to any A1200 in tower ...