How to calculate what type of batteries to use and how many? (Please help)

Hello i currently have an arduino project that im not sure if im powering it properly and want to know how. Im new to the arduino eletronically wise and id appreciate any help.

I currently have an: Arduino mega, attached to speeed seed motor shield http://www.seeedstudio.com/wiki/Motor_Shield_V2.0 with 4 DC motors, 2 mini servos that dont work full time, an ultraSonic sensor that doesnt work full time either, and a pixy cam connected to the ISCP that draws 5V http://cmucam.org/projects/cmucam5/wiki/Powering_Pixy

I understand its a quite full project and would really appreciate any help.

Thanks, Andrew

Please don't double post. It just wastes time and irritates people

...R