The machine heats the water. This takes some time, similar to a tea maker. There are two temperatures, so the time is a little longer depending on the temperature. When the machine is switched on, the water is already warm, which is very helpful when the baby is crying.

It is ready immediately if the machine is always connected to the power supply. If the water tank is empty & you put new water in, it takes a "little" time until it is warm. But when the water tank is full, you can always & immediately let out a shot.

The machine heats up the water. After switching on, it takes a moment.

No, you only have to fill the tank with water, the rest is done by the machine. You can set whether the water should be at room temperature, 38 degrees or 41 degrees.
Once set, the machine does everything itself.
The best investment you can make, trust me.