Thanks everybody for all the very insightful suggestions. I am now working on the reading of the voltage (I am preparing a voltage divider as I do want more than 5V on Vin), and preparing for the reading of the current as suggested above (I may have some questions later).
I have also found a RPM-measurement tutorial that uses the hall-effect sensors, as it was suggested: I am thinking if this is the best way. Any other suggestions in that respect?
Unfortunately, because of the nature of the nature of the experiment itself, I cannot deduce the torque directly from the accelerometer (that was good thinking though!).
Hopefully, I will be able soon to post a few videos with the details of what I am doing