Questions about GvG schedules

The Arena The Arena
1

I have a questions about Siege (GvG MEDEIA/SLIME ISLAND)

If you press Challenge, it shows the challenge conditions which tells you the day and time:

Thurs, Fri, Sat and Sunday
Challenge available from 11am - 20:20

QUESTIONS:

  1. Is GvG only held every Sunday 20:30?
  2. What about Thurs, Fri, Sat, what are those days for?
  3. Also it says available from 11am- 20:20, what about this time?
  4. If we do Medeia, we cannot do Volare island? since both falls in the same category which is Siege wherein we can only do 1 siege per week?