Won't you take a few moments to start a new thread in the "introductions" section and tell us a bit about yourself?
No, don't use redwood for substrate. None of the woods that are considered "aromatic" are good to use as substrate. My favorite is orchid bark, then cypress mulch, but quite a few folks use coconut coir.
(Just a note on posting here. When you ask a new question that doesn't pertain to the original posters thread, its always best to start a new thread. That way more people see your question, and you don't run the risk of offending the original poster)