I think both of you are correct on the pumice. I really like using it for my succulent pots. I do very little watering of the tender succulents, pretty much let them dry out before watering again. But each situation is different.
The only one I recognize is Crassula ovata 'Gollum'. I love it, and seldom water it. Very drought tolerant, and for me it is a slow grower.