If your spa is connected with a GFCI circuit breaker you will not need the GFCI receptacle.
A GFCI device in a breaker is intended to trip the breaker open when a ground fault is sensed in the circuit that the breaker is protecting.
Not that I know of. The largest GFCI breaker I have seen is a 60 amp.
If you're using a GFCI breaker then the entire circuit will be protected by just the breaker alone. Every receptacle, switch, etc on that breaker will utilise the GFCI protection. You may have problems with it tripping if you plug in a motor (vacuum, etc) on the circuit.
If it's a GFCI receptacle and the button is not resetting then change the GFCI outlet.
Not if the GFCI breaker is supplying the circuit you are wanting to put the GFCI receptacle into.
If your spa is connected with a GFCI circuit breaker you will not need the GFCI receptacle.
A GFCI device in a breaker is intended to trip the breaker open when a ground fault is sensed in the circuit that the breaker is protecting.
Not that I know of. The largest GFCI breaker I have seen is a 60 amp.
You need a GFCI outlet at any location that is within 6' of a water source. You also need a GFCI outlet in a room with a concrete floor, any garage, and any location outside the home or under the home in the crawl space. A GFCI outlet protects you from electrical shock near water or moisture. You can protect more than one outlet with 1 GFCI outlet. Connect the incoming power to the LINE side of the GFCI outlet and all the other outlets getting power from that outlet to the LOAD side of the GFCI outlet. That way they will all be protected by 1 GFCI. A GFCI breaker is used to protect an entire circuit and not just individual receptacles. It is often cheaper to use GFCI receptacles than a breaker, especially if "piggy-backed" such as described above. It is also more convenient to reset a GFCI receptacle than to reset a breaker. But your question is "why." From this I suspect you may be misunderstanding the difference between a breaker and GFCI protection. To keep things simple let me say that a GFCI does not work on the same principles as a standard breaker. It provides a much safer protection than a standard breaker. Even with a ground you need GFCI protection as listed above.
Your question is a bit vague, but let's try a two part answer. If you have a GFCI breaker in an electric panel you should only have one connection at the breaker, but the breaker will protect all devices on the circuit. If you are talking about a GFCI outlet, they are equipped to extend the GFCI protection to other non-GFCI outlets by using the proper "output" connection on the GFCI.
No, you could use a GFCI circuit breaker instead.
There are tow places to put a Ground Fault Circuit Interrupter. There is a GFCI breaker which would be installed in a breaker box and a GFCI outlet that can be installed anywhere. Most GFCI outlets allow you to connect regular outlets to the GFCI and those outlets will also be protected.
GFCI Breakers are quite a bit more expensive than a GFCI outlet. More often than not a typical residence will need only a handful of GFCI outlets that combined together will be cheaper than a GFCI breaker. If you need to protect a series of outlets with GFCI protection you can simply connect the rest of the outlets on that same circuit downstream from the first outlet on the line and make that the GFCI. All you have to do is connect all the other outlets to the LOAD side of the GFCI outlet. If a GFCI fault occurs in any of the outlets down stream they will trip that very first GFCI plug you placed and keep you safe.
Deoends on code you are governed by. In USA, a GFCI outlet or a circuit controlled by a GFCI circuit breaker would be required.
If you're using a GFCI breaker then the entire circuit will be protected by just the breaker alone. Every receptacle, switch, etc on that breaker will utilise the GFCI protection. You may have problems with it tripping if you plug in a motor (vacuum, etc) on the circuit.
Yes you can but the electrical code does not require it. To use one where it is not requested to do so is just adding to the over all expense of the project.