Well, today I managed to put the bluetooth control part of the platform to work. It is very barebones but it will improve as it needs. Basically, I used Joystick bluetooth Commander android's APP to send joystick data to arduino. It outputs from -100 to 100 in each axis X and Y, so I needed to make some math to control the 2 motors speed.
The app has a very nice forum post at arduino forums, Some of my code is based on the demo sketch so copyright goes to the creator (code doesn't have info on the author).
Hopefully tomorrow I will waterproof and attach the platform to some bottles to do my first real life tests... lets see how it goes.
A video from the test: