There really isn't anything you couldn't plug into a gfci, but are usually 110V small appliances, and they are most common in bathrooms or kitchens (places there are water) to protect the person using an appliance such as a hair dryer from electrical shock.
Yes you can. Lots of blow dryers have GFCI protection built in.
Yes.
In a word NO, that will not cause either GFCI to trip. The correct term is GFCI (Ground Fault Circuit Interrupter)
If the appliance is used in a bathroom it must be GFCI protected.
If your spa is connected with a GFCI circuit breaker you will not need the GFCI receptacle.
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.
Ground fault circuit interrupter. Turns off the the power to the outlet, when the there is a leakage in current. example when you stick your finger in the outlet and the current leaks threw your body
NO - it is not safe to do that. A GFCI breaker is only a secondary safety device and your primary safety still depends on the earth wire in a 3-pin supply.
Connect incoming power to the line side of GFCI outlet and plug Jacuzzi into the outlet. Must be on a dedicated circuit. If it has a pump and heater then each one must be on dedicated GFCI protected circuit.
Yes it should .
there should be 5 wires, hot and switched hot for the switch and hot, neutral and ground for the gfci receptacle.
You can plug US appliances into plug sockets in the US. You can also plug them into sockets in Mexico, Canada and several other countries that use 110 to 120 volts mains electricity.