1. This means that the ground was so dry that even if it rained a lot, the ground wouldn't get muddy. You should think of brown, almost dead grass just soaking up any rain that touches it. It's just poetically describing the ground at Parker Head as being very dry for a long time.
2. This is just describing how he walked. Forward-falling is how pretty much all humans walk, falling until the foot they are stepping with hits the ground. His arms swinging with a contained reserve in his hands mean his arms were moving back and forth, a bit stiff and his hands were open but most likely slightly clenched.
The first description is just setting the scene. Authors frequently use complex descriptions so you can see the scene in your head almost as if you were there. The second is more of an emotional vehicle that shows you how he is feeling, based on where it is in context of course. I hope this has helped.