Replace the 30 Amp Breaker with a 15 Amp breaker.
There isn't a formula, but the general rule is that you allow for 1 amp per outlet and you load the circuit to 80% of maximum. For a 15 Amp circuit you can have a maximum of 12 outlets.
15 amp outlet on a 20 amp circuit.
The majority of the circuits in your home are run on 15 amp circuits.
7 on a 15 amp circuit and 9 on a 20 amp circuit.
Not unless you change the wiring for that circuit. The breaker protects the wiring and if you install a 40 amp breaker on a 15 amp wire circuit you will have a fire in your home.
A 15 amp dedicated circuit breaker should be used for the dishwasher. The disposal can be wired to the general kitchen 15 amp circuit.
You can but it is not recommended.
Eight on a 15 amp circuit, tweleve on a 20 amp circuit, including the gfci receptacle itself.
To trip when current is in excess of 15 amps and protect the circuit components.
A plug and play 15v amp circuit is one that you can simply plug in. It has a three pronged plug so no special wiring is needed.
Yes, the amp rating is a measurement of the highest amp load it should carry. So a 15 amp appliance will work on a 20 amp socket but you wouldn't want to use a 20 amp appliance on a 15 amp socket.
In North America you would need two 15 amp breakers to obtain 240 volts. The wire for a 15 amp circuit would be #14 AWG. So to answer the question, yes a 240 volt receptacle can go on a 15 amp circuit.