Spotlight (mds) Status, Ejecting Volume

Currently I cannot eject a volume because apparently Spotlight is indexing it. Is this expected behavior on El Capitan? Shouldn't Spotlight resume indexing later in this case and not prevent ejecting the volume?

This led to a couple of observations / frustrations / questions:

1. there seems to be no way to see the Spotlight indexing status via the Spotlight menu. Is this true?

2. I am pretty sure that Spotlight is the culprit because "sudo lsof | grep /Volumes/myDrive" returns are all for the process mds_store, except for one entry for Path Finder. After quitting Path Finder, I still could not eject the volume.

3. How do you interpret these results of "mdutil -sv":

Scan base time: 2015-10-14 09:23:42 +0000 (90 seconds ago), reasoning: '(null)'

What's the "base time" refer to? Is there any way to get a progress estimate from that? What about the "null" reasoning?