5 cell packs are 6v, 4 cell are 4.8. mAh rating is duration of the battery, get the most you can afford. I use 1400s for racing (good duration and quick charge time), so you don't 'need' to go any higher than that, such a battery will give you about two hours constant use with stock servos. When you upgrade the servos they will use more juice and the battery won't last as long, but even with my racing digital servos, I'd say I get about 90mins out of my 1400s. The current delivery is down to the quality of the cells and is not quantifiable usually. If you get a good brad like team orion, this is not going to be a worry. Especially with touring cars, which much less demanding requirements on the servos than buggies or truggies for example. Those 2/3A cells deliver enough current for off road, so on-road they're more than enough. Not a worry. By the way, in anticipation of your next question, when you want to upgrade the steering servo, get one that has a torque rating of around 100oz-in@6v, and as fast as you can afford. Just about the best touring car steering servo on the market is the Futaba S9451. In order to successfully use such a servo, you need to be able to set the 'endpoint' of the servo travel in both directions. If your stock radio does not have this adjustment, then it might be abetter idea to upgrade the radio first, before the servo.