Help with 16:1 Mux IC Wiring
Here is what I have so far. Is this correct?


Looks fine to me. Another option would be to share the COM pins and drive EN on the multiplexers to read from one at a time, but what you have is fine.


  However I feel like these are not the same as the actual ICs.


The Sparkfun breakout boards you're referring to are essentially "pure"  breakouts. The only additional things on the breakout board are:


A pulldown resistor on the EN pin, which is unnecessary if you're driving that pin, and
A decoupling capacitor on VCC, which you should have in your circuit as well. (Just connect a small ceramic capacitor between the VCC and GND pins on each IC -- 0.1 µF is about right.)



  How many of Mux can I daisy chain?


Plenty. :) You'll run out of input pins on the Teensy long before you hit any fundamental limitations of the multiplexer.