1. Gulf Air had an accident a few years back. CFIT into the water on an A320, all were killed. As a result of this accident, it was decided at a very high level in Emirates that FO's should serve 4 yrs (since reduced to 3 yrs) in the company before upgrade. Current time to command was < 2yrs at the time. An incredibly arbitary and pointless limitation and one that is still in force.
2. Many questions in one. Emirates is short of Captains, FO's and trainers....probably short in every other department as well. Incentive for Emirates - they need pilots now, even if they come on LWOP from NZ and may go back. An assumption has probably been made that a number (??) will stay. Incentive for NZ - much better to give LWOP for overstaffing than downtraining and furlough.
3. Everyone has their own reasons but I doubt leaving NZ for lifestyle would be one of them.