Hi - have been looking in JAL Mileage Bank as a way to use redemptions on partners such as EK.

In the partner award table, I can see the following;

The required mileage is determined based on the distance of total award itinerary (total of sector mileage for each sector and surface sector).

1) Does this mean I can book (for example) - SYD-BKK//BKK-DXB-IST//IST-DXB-SYD, giving a total required mileage amount of 18,932 miles giving a redemption cost of 100k in J Class?
2) Can airlines be combined on award redemptions? Say for example SYD-HKG (CX)//HKG-BKK (EK)//BKK-SYD (QF). Do the same redemption rates apply?
3) Pursuant to the above, are stopovers allowed on awards?
4) Is there a way to purchase miles in JAL Mileage Bank (other than transfer from hotel programs).
5) What is the difference between "available" and "vacant seat waiting" when booking online?

Thanks in advance