Drobo share partition size will/could change when migration from gen3 to 5c?

My drobo share partition set as 16TB in gen3 and the space is run out recently. therefore, i plan to have a 5C then move all drivers from gen3 to 5c to add more drivers in the future.

  1. after migration to 5C, what size of drobo share partition will show up? 16TB or 64TB?
  2. if size still keep in 16TB, how can i expand it to 64TB without data lose?
  3. if i replace to large driver 4TB4–>8TB4 for example, will the size of drobo share partition auto expand?