Then, what is the thing over the stove called?
A kitchen hood, exhaust hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration.
Beside above, do all stoves need a hood? Most residential building codes do not require a range hood above a stove or cook top, but you'd be wise to ensure your locale is not the exception. Even if it's not legally required, you should think long and hard before forgoing a hood altogether.
Secondly, what is the point of a pasta arm?
Since these faucets allow you to fill pots and pans right at the stove, this allows your sink to remain open for food prep and cleaning. Additionally, a pasta arm will help reduce the chance of spills that may happen while you're carrying pots from the sink to the stove.
Where does the stove vent go?
Range hoods are vented up through the roof or out through an exterior wall. Look for a metal duct going through the cabinets above or an exhaust cap on the exterior wall behind the range hood. You should feel air being blown out of the exhaust cap on the roof or wall when the fan is running.