I also am fairly new to digital photography and have read that when using a tripod one should turn the image stabilization OFF as it too can degrade image quality.
This is really a neat picture, in my opinion. I suspect these are roofing nails from which the shakes have pulled away from the sub-strate material. I think I also see some felt paper along the left border and remaining shakes along the top. No shadows, however. Softening or cropping out the bright spot at the top mightg help. It was somewhat distractiing to me, but I like the image a lot.
I have never used HDR processing and know verey little about it. Your application to the two photos that I have seen is beautiful. I do agree with some of the previous comments regarding taking the tree and wagon wheels "off center" and cloning or cropping some of what distracted me. I have taken the liberty alter your work in an attempt to demonstrate--I hope this does not offend.
cropped and cloned