Hi,

I'm considering buying a few ESP8266 cards to build sensors and feed my Home Assistant with data via MQTT.
Anyway, I have a few questions I wasn't able to find answers to here or on the Internet.

If I buy a NodeMcu Lua development board, as linked on the ESP8266 page on this site (the one sold on eBay by alice1101983), it seems to ship with a USB cable ("USB-TTL included, plug&play"). Do I have everything I need to start, or is this cable just for communication, and I need to power the board externally?

Speaking of powering the board, from what I read I can power it with 3.3V or 5V, am I correct? The board has a micro-USB board, can I use this port to power the board?
Once I go "production", I guess I can power it using the 5V+GND ports on the left, or the 3.3V+GND ports on the right?
Do you know any affordable way to power the board? I would find it unfortunate to buy 5€+ chargers to power a 3€ board.
What about using batteries? I've read that the board can go in some sort of "sleep" mode. Some of my sensors could easily go to sleep and wake up themselves every 5 to 10 minutes, report what it needs to, and go to sleep again.

Finally, on the network side, if I'm not mistaken, the board integrates WiFi, so why do you advise buying NRF24L01+ boards? I just want the boards to connect to my WiFi network, not communicate with each other, so I don't need it right?

I know this isn't a community dedicated to the ESP8266, but seeing some of you are using this board, I hope you might be able to answer my questions