"By Dao are you referring to fundamental reality?"
Almost. But for a taoist it would be a bit more mysterious than that. While it is based in reality, for it controls the flow of nature. It can also be mytically used for "magical" purposes. Healing, increasing strength, and such by use of chi.
"Ask Nature"
Very close. While a taoist would see that nature is one with tao. Tao still controls nature. So a taoist would look at nature and say, ask tao.
"I know you're using the term "energy," but I've always understood "energy" as the force that causes a capacity to do something."
Same thing, chi is the energy that is produced by tao that causes everything to do something. Change never stops happening. Nothing stays exactly the same for even a second. So this "energy" is the force that causes a capacity for everything to do something. Chi to a taoist would also have more mysterious capabilities than just plain energy of course. But that gets into religious taoism, where I do not dwell. Chi vampires, immortal beings, etc... I just focus on the simple concept of Chi Gung. In which you work that chi around your body for health and enlightenment.