These would be uncommon, appearing in forest, jungle or plane biomes. They would have no leaves, being only a tree trunk. The trunk would be 2-4 blocks high, possibly a 1 block branch. The rotted logs would be the normal texture edited with green decay, and have a hole through them. They would break at the same speed of ice, because usually dead logs are flimsy, damp and weak. When broken, they would drop Log Mush, which would act as a fertilizer for plants, like bonemeal. You can place the Mush on the ground, and it would attract silverfish if they were added.
I guess so, it could be used in things that have to look old or abandoned