Book formatting (print)

I'm a long way from holding a copy in my hands, but I am working on getting my books out in print through the POD company Lightning Source. As I edge my way towards it (lots of other things going on, too) I find myself asking if the instructions on formatting the inside of the book have everything I need to know. They're very simple and I have a hard time believing it's that easy. (lol) Also, I'm wondering if anyone can recommend a good, free book formatting program? I don't want to submit a book innards file to them and then have to completely redo/resubmit it. Basically, it's a LOT cheaper to get it right the first time! Thanks for your help. :-)