Following the MQTT example of the Intel Edison + Arduino you will be able to control just one variable. If you desire to control more than one, you should parse the data received (subscription) per the variables desired, then in based on the last values obtained control the actuators.
If you are not a technnical person the point above can be a little bit frustrating to get started. For this, I also recommend you build you own example to make the GET request to Ubidots based on this example.
Please reference to the Ubidots REST API Reference to learn how to build the GET request to Ubidots properly!
I hope this would help you
All the best,