Dynamixel servos use a ttl serial connection. Each digital port can be one. So yes

As josh says, all 24 ports will control those servos you won't need the uart for them specifically

Dynamixel servos appear to be Smart Serial Servos. The concern I think is can the UART port be used to receive the Feedback from these servos as well as send commands. The servos can feed back position, temperature, load, and input voltage, etc. The serial bus they use appears a little strange as well being a multidrop serial TTL daisychain connection. Very Pricey I know if I used one I would want to use as many features as possible.

Dynamixel is brand that brings features of larger professional servos to equipment comparable to the size and power of RC servos. The top features are position feedback and load from what i have seen. Lots of walking robots use the so they can compensate for being bumped or a leg or foot touching a obstacle. They can feed that back without external sensors. It's pretty cool but utilizing those features effectively can be complicated.

@Josh, Is that how they balance as well? I figured they had a gyroscope sensor or something like that. It's been a while since I've read about them. Dynamixels were one of the main sources that inspired me to finally start exploring robotics.

@Anybody, Will the new EZ V4 read all of that info through the 1 data wire or will it just read position like the V3 does? I'm not sure how or if V3 works with dynamixels or not but, if it did, I'm guessing it would only read position.