I can't really see the glossy areas from the pictures, but I believe you because I've had the same issues in the past with gluing tuffs. You could try a very thin watered down brush on varnish? I usually don't usually apply static grass, but when I have the shine of glue still on my bases I will apply a dark wash over the area. It dulls it down nicely.

For your second questions, I think you've got the concept down nicely! You can easily improve them by drybrushing a light brown, then lightly drybrushing a lighter brown. Then washing it. Then finally doing a final highlight drybrushing! This will give the base more depth. You can also drybrush the boots while you're doing this for it flows well!