The A310s are freighters and were just bought a few years ago. They are a versatile aircraft for some regional freight markets and other specialty flights. The company has been pretty good about letting guys hired on the A310 go to other fleets after about 3 years on type.
The A380 will be operated as a separate type from the A330/340 fleet, which is operated as a single fleet. The A330/340 guys already have to deal with three different models; the A330-200, A340-300, and A340-500. The current plan is to take A340 qualified pilots to the A380 for the first year of operation, after that they will allow some senior B777 pilots over.
Emirates nominally operates with freezes on type of varying lengths, but that is waived for new types. The true policy is they move people where they need them. Sometimes it works out, sometimes it doesn't. The official written policy is that a First Officer is frozen in type for 3 years from final check and Captain is frozen for 6 years.
There is a policy for direct entry first officers on the A380 which states a minimum of 1000 hours on A330/340 or other widebody jet, among other requirements.
Typhoonpilot