If you look on Tower's website, there is a list of things that the item "includes", such as batteries. They list 600mah batteries for both Tx and Rx. But, since you'd be buying batteries from another vendor, you can definitely wait to get them; it will be days to weeks before you are ready to start installing batteries in anything.

I think I got the 1.4 factor from either Radical RC or from Battery University (maybe they're the same?) Either way a good reputable source. And like Missileman, I just charge a few hours over what the math says to charge; the factor of 1.4 is just a way of explaining that you need to charge longer than what the math says.