I would hold off on buying anything until you get a firm grasp on what you are going to build. I would suggest organizing a complete parts list for the entire build before buying anything as well. I was taught by an expert on here to draw an entire schematic of your car., and I thought he was nuts, but it forced me to see the big picture. It sounds like you could really benefit from a few hours of reading about other peoples builds on here, the wiki here, and evalbum. You will be glad you did. If you have questions, keep asking... I know from experience what it is like to be new to EVs, so I will answer everything that I can.