air space vs. insulation

[jsb]

In controlling sound and vibration from an upstairs
apartment I plan to use the isolation clips and metal
channel and 5/8 drywall.
Question 1: - should I fill the joist space in ceiling
with insulation or leave as air space.
Question 2:  Should I add homosote sheets right before
the drywall? or would the sound mat material be a better
choice?
Thanks
Jsb