MAC address is already made available via the app. Look under device settings either via a website https://app.rach.io/ or Android / iOS applications.
Not sure what you could do with information on the IP address. Rachio does not make any useful data / interface available directly via the controller.
With such large network, I recommend you get one of the free network scanning applications, such as Fing (for iOS) or (for Android). It had no issues not only quickly locating the MAC / IP information, but also correctly identifying it as a Rachio controller.