Sample timing

I have been reading the register description doc for the MPU 9250A (RM-MPU-9250A-00.pdf) to try to figure out the sample timing.
I am confused as to the exact meaning of the values in the tables on pages 13 and 15. These are the tables that list Bandwidth, Delay etc vs FCHOICE and DPLF_CFG.
1. What exactly does "Bandwidth" mean? I would expect it to be in some unit like bits per second.
2. From when to when is "Delay" measured?
3. I assume that Fs means "sampling frequency". Is that correct? How does this relate to the SAMPLE_RATE listed in register 25?

I have read the docs for the magnetometer and I understand what initiates a sampling of the magnetometer (writing the MODE) and how I can tell when the conversion is done (reading the DRDY bit).
How do I know the same for the Accelerometers and gyros?