Power needs, motor drivers, and more..

Thanks Doctor! Switching to the 4xAA battery pack indeed gave it a much better torque!

May I ask a couple additional noob questions?

1. If I replace the battery pack with a 9V battery will I get even better results? Or I will just burn something? (Am I being extremely naive in thinking more V == better torque?)
   
2. That boost converter you said, most the ones I find seem to output 5V (like this LiPower Boost Converter). This one seems to be regulable up to 35V this one. Is that the one you mean?
   
3. Instead of the boost converter, would it also work to get this 2C LiPo battery?
   
   

Thx!