It is only an overflow, you can connect it to a drain or outdoors into the woods. With normal use and the fan going all the time you most likely will not have much overflow problems. When the toilet is plugged in it has a heat unit that keeps it at an optimum temperature to minimize fluid build up. We drilled a hole through the wall and ran the tube to the outside. Check out youtube on composting toilets, the reviews and tips/tricks. It is our go to for product reviews, and hints for everything we have questions about.
To vent the toilet, you would run a 2 inch diameter pipe from the top of the unit either straight up or through a side wall and up. It needs to end above the highest point in the roof.
No, it is not ADA approved.