Some more questions to clarify:
- What version of the adafruit motorshield (is it v1, v2 .. ?)
- Why couldn't you use the Pololu shield? (-> would be easier than to rewrite/modify the existing code)
- How do you want to power the project (2 Li-Ion batteries in series or parallel, how much voltage do you want to achieve, what voltage do the batteries come with) ?
- Do you exactly follow the Instructables schematics?
- Do you have already the bluetooth module?
- To move the motors: what kind of bluetooth transmitter will you use (to send direction signals etc. via bluetooth to the bluetooth receiver connected to the Arduino) ?