am I right in saying I’d need an xBee sensor (XS-Z16-CB2R), the xBee WIFI module and an xBee explorer so that I can can communicate with the xBee WIFI module from my PC?
XBee sensor (XS-Z16-CB2R) works on different communication protocol called Zigbee. It can’t talk with WiFi modules.
You can either get separate compatible temp. & humidity sensor and connect them with IO pins of WiFi module.
Or another option is to get XBee Sensor and WiFi module(Through Hole). Now open Sensor’s box and replace Zigbee module with WiFi module. You don’t have to get explorer board in that case but this will void warranty of XBee Sensor.