Can ceramic floor tile be used on my shower walls?

Yes but you may need to support the tile as it sets up. I ADVISE you to deal with the termites and mold and ventilation, or all those heavy tiles will come tumbling down on someone in the shower or you won't be able to sell because it won't p an inspection. The panels are available at Home Depot but will get nasty if you don't deal with the mold first.