Is the Data in the Hierarchy Live?
Yes. The information displayed for each row of the hierarchy is a live pipe right from your tables. So if you change your data, the hierarchy will reflect those changes for existing rows as soon as anything is touched in the hierarchy: an item is opened or closed, or the "refresh" button is clicked.
Is you add or delete records, those actions will show up when that section of the hierarchy is rebuilt. (Note that this is also when items are sorted.)
So the top level items are built when the hierarchy is first drawn (on "build...", "open all", "open top", or "close all"). The hierarchy is also rebuilt when the Outline or Legal formats are applied.
Items below the top level are built on first draw and then when their parents are opened or closed.
So if you want to refresh a particular section of the hierarchy, just close and reopen an item's parent. To refresh the whole hierarchy click "show hierarchy".