A quick update: today I found a simple way to post status changes or notifications using Arduino. It’s by using a service called pushingbox:
https://www.pushingbox.com/
basically it allows you to use a unique device id and a simple GET (or POST) command to post status changes, and it can be hooked up with email notification, or posting the data to Google Forms. More specifically, when external IP (eip) changes, the firmware can send a GET request such as:
http://api.pushingbox.com/pushingbox?devid=xxxxx&eip=12345
where devid is the unique device ID (created by pushingbox). You can set it up such that it can either send the new eip to your through email, or post it to a Google form. This is pretty nice because it delegates authentication (required by Google forms) to pushingbox, and you can associated multiple services with the same request (e.g. send email notification as well as posting the data to Google form).
Because GET request is already supported in the firmware (this is how it performs weather query), it would be fairly easy to add support for it. In fact this way the firmware can also easily send notifications about zone status changes and so on.