1. Water and ice. Sometimes the smoke can get hot and might burn your throat and feel bad... Not a good thing. The water and ice will cool and condense the smoke for a better hookah experience.
2. I store mine in a cupboard. I've heard of keeping it in the fridge, but I've never tried it personally. But I've still always gotten good results.
3. Herbal shisha is not worth the money. I tried it, unfortunately. I hated it. Smoke the tobacco. That's my opinion.
4. Sounds to me like you're cleaning it right.
Hope this all helps. Enjoy your hookah!