I used it with my cresty for years. It holds moisture well without molding. The only disadvantage is that if the cresty misses a cricket, they may get a mouthful of substrate (no biggie).

That's a cool question. I used to grow shrooms in college, and I used brown rice cakes as a substrate. I wouldn't have thought to use this as a substrate. I'd offer that this likely has some sort of anti-fungal properties, whether they're synthetic and added, or if they occur naturally I don't know, but I've kept tarantulas on this substrate for years, literally, and it never grew any fungus, even when consistently damp. IMO, this indicates there's no nutrients available or it's a pro fungal environment.

yes it holds heat and i have 2 hermit crabs that love to burrow in this.

Yes. It holds moisture, helps with odor control, and helps remove shedding skin too.

No, loose substrate is not recommended for bearded dragons. Acceptable substrates are reptile carpet, tile, paper towels, or non adhesive shelf liner.