BartW,
Glad you were able to figure it out! We do have documentation on the mcDemo205 (product specification found here:
https://static1.squarespace.com/static/5644f11fe4b0d6ca7d80d351/t/582f8781e4fcb5e251bc00a4/1479509893678/mcDemo205+Product+Specification+V0.3.pdf) and you can also check out our support and resource pages on our website to find links to all the documentation that we provide. That document provides a bunch of information about the device and also includes multiple examples.
That said, I will make a note to ask our team to include the SIGFOX functions to make this easier for clients working with the mcDemo205.
You can (As you found out) hit CTRL + Space while you write code to get suggestions. See image below. I have also attached an example code for using the GPS, temp and battery voltage functions and then relaying that through SIGFOX
Yes, you can use the GPIO for the interrupt!
You need to define the pin you want to use as an input. Setup one of the pins that is available as an input (High, pullup, etc) and then raise an event depending on the polarity of the interrupt (IE pinfallingedge or pinrisingedge). When that event happens, that is your interrupt triggering. You can then write your ISR code in this event.
Hope that helps!