The casing of the drone is not of importance here. What i mentioned above is for the Teltonika FM1100 casing that you should remove and place the PCB of FM1100 only inside the drone casing. This will allow you to monitor your drone using GPSGATE. As for the Aduino part, well you need to read a bit on that. A good start for your project will be the Arduino FIO with XBEE wireless (around 80$) for both. Check it out first, get an idea then let me know. Just for your info, the most important issue for drones that uses Arduino or micro-controllers is the stabilization part but you are still very far from that.