Facing some questions regarding my energy meter project
The most reliable way would be to buy an energy meter with dedicated serial interface and connect it to your Raspberry-Pi. As you said, you will get a lot more information with a digital meter than from an analog one. But they are also the most expensive ones.

Some cheaper meter don't have a serial interface but a so called S0 interface. 


This is basically an open-collector digital output which closes about 1000 times per kWh (depending on your meter). With an external pull-up resistor, you get nice pulses which you could read with your Raspberry-Pi and an GPIO library with interrupts. You can use pigpiod to generate interrupts and measure the time-interval between two consecutive pulses. With this, you can calculate the instantaneous power consumption.

If you have an analog meter with dial pointers you could try to read those pointers with some kind of short range distance sensor like this to generate pulses every revolution.