1.A data plan has to be put in place: you need to buy a plan with SIM card to be installed on the machine. The data plane need to be with 3G.
2.WU data upload protocol is built inside the machine, and as long as you have your WU ID and passkey entered correctly, the system will push data to WU server. As to detailed data upload protocol, you may find at:http://wiki.wunderground.com/index.php/PWS_-_Upload_Protocol
3.You may find more info about the system by looking at the manual:http://www.ecowitt.com/upfile/201807/WH6006E%20Manual%20Update%20Version%2020180709.pdf