For insulation levels, see this Zip Code specific calculator

Below are the sound transmission values for various floor and wall material combinations. Note that insulation in walls and floors does little to change the values.

Source: City of Vancouver Noise Control Manual

Here is a link that might be useful: Noise Control Manual (pdf)

You will also need to provide a fire-resistance rating between the dwelling units.

Since a multi-family apartment building must be designed by an architect who is required to meet the commercial building code standards for sound and fire separation as well as energy conservation, that's the best place to start.

I'm interested to know what you'll need to
do to insulate cinder blocks.

where are you located?

best of luck