Adding additional components to Smart Robot Car Kit

Hello! My name is Bill. I've bought the Smart Robot Car Kit 3.0 Plus from Elegoo and have successfully built it, and ran it. I've looked over the code, and everything is great! Bluetooth works well, obstacle avoidance is wonderful. All in all, I love the product. Hopefully there is someone here able to help with a few of the questions I have.

I want to do more with it. I've done a bunch of googling, and can't find the answer to my questions. What I want to do is add more components to it. I am looking at the I/O expansion board, but cant figure out how it works! I've attached an SD card reader module to the expansion pins, but when I try to drive the car, it doesn't work. I assume this is because the pins i am connecting the SD card reader to are in use by the motor/other parts of the driving assembly. How can I use the expansion board to add more components to the car?

I am also trying to find out if I need more power to do so. Again, I can't find how much power the car is pulling from the battery, but no luck. My next idea is to add another UNO board to the car with it's own separate power circuit. Is this necessary, or is the Lithium Battery able to power more modules? Thanks in advance!

Documentation for the project is found @
(Elegoo Smart Robot Car Kit V3.0 Plus)