I read a lot of the fantastic information shared here, but I didn't see anything about what to use when cleaning the habitat.

Yes, clean up poop and replace substrate as needed.

What about the frequency of replacing all of the substrate? Should this be done quarterly? Monthly? For an adult, in conjunction with cleaning up the shed?

For the terrarium (mine is glass), what should be used when cleaning the glass? Simply tap water and a cloth? Or soapy water (and please be specific on what kinds of soaps are good if there are good and bad soaps)? Or should I be particularly thorough and use a bleach cleaner?