If you decide to go for LiPo (which TBH is what most people use for racing these days) have a look at this guide. It was written by an RC helicopter flier but all the info is basically the same for cars:
http://www.rchelicopterfun.com/rc-lipo-batteries.html
It's a bit of a long read but when I started racing in 2011 I knew literally nothing about LiPo and I just basically read it a few times and got started, everything you need to know is there
