What size water heater you need depends on how many people are in the building, how many bathrooms, size of shower heads, dishwashers, washing machines and whirlpool baths. Yes draining your water heater every 30 days cleans out the sedate that causes your water heater tank bottom to overheat which can lead to premature tank failure. If your water heater makes gurgling sounds it usually means there is sedimate built up in the bottom of your heater causing the water at the bottom of the tank to boil and the gurgle sound is the bubble created by the boiling water rising to the top. The temperature should be set so it just hot enough to satisfy your needs. Usually the choice is already made for you, but if you have a choice here are some things to consider.
Gas is cheaper to use ,and makes more hot water faster.
Gas heaters require gas and flue piping they can not be installed in a living area, bathroom, or bedroom .Flammable liquids cannot be used or stored near a gas water heater. Electric water heaters are more expensive to use but only require electricity and can be installed just about anywhere. In this application a electric water heater may be more efficient than a gas heater . Roto Rooter is a company name for a drain cleaning company that has been associated with cable drain cleaning. The term roto rooting refers to cleaning a drain or sewer with a cable type drain machine that turns a special cable with a cutting head on the end.