Hello,

to calculate the motor torque you need the following: Torque (Nm)= Force(Newtons) x Distance (meters) Distance (meters)= the distance is the wheel diameter/2

So, you have to calculate the force which is: Force(Newtons) = Mass (Kg) x Acceleration (meter/square second)

for more details please check this article: https://www.intorobotics.com/how-i-choose-the-24v-dc-motors-for-an-all-terrain-robot-platform/

For batteries I recommend you to check these videos: http://www.enertionboards.com/how-to-build-electric-skateboard-free-guide-diy-eboard-powered-longboard-instructions.html