Japanese art forms that incorporate living plant material into a dish garden setting or a landscape in a tray or on a rock are called either kusamono or saikei, and there is some info available on the internet. Kusamono leans heavily toward plantings of small native plants in bonsai dishes or trays with an emphasis on grasses. Saikei, is usually a planting on an interesting rock (most often to represent a mountain scene) or a planting in a tray that incorporates rock or other natural material and is presented as a miniature landscape scene.

It sounds like the plant you described might be schefflera arboricola.

In most instances, a more natural appearance is achieved if no waterproofing is used on the rocks, and adherence of epiphytes would certainly be improved by using materials in their natural state. The exception would be when using wood products (old branches, stumps, etc.) that contact moist soil.

There are few mosses that will grow indoors w/o constant misting.

There may be books available at the library, on e-bay, or through a book seller. You can also search the net using the words provided above as key words for photos and additional info.

Al