My spa is set down into the deck so that there is about 4" above the surface of the deck. You should check the installation instructions as to what kind of support it needs. I do not think it wise just to set it on top of the deck, but don't put it below ground level. It drains via gravity. Mine had specific instructions as to where 4x4 stringers had to be. Even a relatively small spa like mine is heavy when filled with water. All of the filtration is built into the spa. You simply fill it with cold water, turn on the heater, add the chemicals, and let it heat. Mine takes about 24 hours to get hot. When you drain the spa, you can let the water go onto the lawn, but you need to be sure there is not a fresh dose of cholorine in the water when you do. You don't have to drain it very often, just add water when it gets low and keep the chemicals up to proper levels. Chemicals are added by just sprinkling it into the spa with the pump running, no special equipment required. Your dealer should give you specific directions on installation, chemicals, etc. for your brand/model spa.