Saul,

Read it again...it says two 4s in series for an 8-cell total. This is my best guess. It may actually use 8s to 10s depending upon my measurments. Sometimes the Kv rating on motors is not always accurate so it is important to take measurements of current, power, and RPMs.

A 101mm fan is the maxiumum that will fit. A smaller fan can be used in many applications, especially if it is more efficient and more powerful. Sometimes a smaller fan can be used to reduce weight as well because the motor, ESC, and batteries weigh less.

Regards.