The consoles work as one way recievers so you can add as many consoles as you like. The sensors working with stations that have the small, "3.0" logo on the front will work with any of the WMR80, 88, 90, 100 and 200 stations. This includes the anemometer, temperature/hygrometer unit, rain gauge, UV sensor, and any additional temperature and humidity sensors.
When you change the batteries it automatically goes into a sensor scan mode. You don't have to puch the "search" button. The only time you need to push the search button is when any of the sensor's batteries are being replaced, or if a sensor is not communicating smoothly. This happens to me all the time. Replace the batteries it should be fine.
I'm not shure the OS. sensors and solar cell are capable of charging. The solar unit only provides power during the day so the batteries are only used at night which is suppost to increase the life of them if they're not working 24Hr. NiMH won't make any difference.