On the HPS site, there is
a few documents that would help you make your mind (That is how I did it).
The planning guide is the one that I have in mind.
A word of cautions: DA is nice and on some aspect fairly in-depth. My biggest beef about DA is the fact that UAV have to be micro managed, which isn't what a force commander should worry about. Another drawback is that it isn't being developed anymore, and the community playing DA is small and getting smaller.
On the plus side, this is a style of gameplay that you will not find in any other title. If you are interested in modern operations and can spare the money, it is worth the purchase.
One of my initial motivation for beginning my own wargame project (see link in signature) was to extend DA's feature set. I'm not there yet, though...
BTW: if passing along a copy of the manual isn't illegal, I can give you a copy. I don't know if it's OK, however. It would make sense for HPS to let you look at it, though.