Does turning off WAAS turn off ADS-B out as well?
This depends on the ADS-B receiver that you have, but if it is still receiving position information, but the WAAS portion is missing, you will get a lower NAC/NIC/SIL in the broadcast message. If you disable the GPS completely, the ADS-B will continue to function however the SIL for position will be the lowest level (likewise for NAC/NIC). The ADS-B will continue to function (as in send messages) but the position reports will be unavailable. 

It's important to note that your transponder is still a Mode-C transponder, even if the ADS-B fails (completely or partially). You should inform ATC that you have an ADS-B or GPS failure and they will inform you if you are cleared to continue or not. 

Really though as far as this is concerned, creating an actual failure is very much not recommended. If I were you, I'd just say "let's pretend that you have a RAIM message about your WAAS, what are your new minimums?" Creating an actual failure is something like pulling the bulb out of one of the gear indicators. It might be a "teachable" moment at first, but really just creates a distraction that can be done in other ways. What happens if the circuit breaker fails and the weather actually drops? Now you have a real problem...