Thank you for your response.
Outside power suply is not an issue, i havent yet decided which power suply i will use but it will be anywhere from 10 to 90W capable. I will then use step-downs to get 3V for relay and 5V for ESP8266. The only issue is if ESP8266 will be able to handle the load i put on him.
The relay board i am using is in the link below, it uses 2x JQC3F relay (full name written on it is JQC3F-03VDC). Sadly i couldnt find any information on how much mA the diodes draw, but considering that a very bright led light can work on only 5-10mA, i really think i am safe there. I will try to measure it with multimeter but the current might be so small i wont be even able to detect it.
2 channel relay - link to aliexpress
As for those 4 LED lights and 4 sensors i mentioned, they will be powered by ESP8266 board. So total wires going into ESP8266 ground pin will be 10 - 4 from LED lights, 4 from sensors and 2 from the relay control pin. I have to admit i am not in the clear here ... i always thought the current that comes through the + wire into a device and then goes out of the device through - wire into the ground pin is the same. Am i wrong here ?
Like i said i will only use 2 LED lights at once and i will use such resistor to limit current draw to 5 or 10mA, which as you said will be plenty bright enough. So that is 10mA per pin and 20mA together for the board. As for the 4x DHT22, the datasheet says 0.3mA per sensor while measuring, so that is 1.2mA together and not even worth mentioning, besides, DHT22 are 5V tolerant so i power them by 5V pin on ESP8266 board. So if we assume that relay uses almost nothing to trigger the 2 diodes, sensors use 1.2mA and 2 leds use 10-20mA, that is combined at most 21.2mA + diodes, which is in the safe area, right ?
It would be great if there was a simple explanation for ESP8266 board. I have been using those boards for years and they are fantastic for their price of 1.5$ on aliexpress. But it would be great to have a simple datasheet i could trust for the whole board, to see how things are connected and to be sure how much i can draw from any single pin. Because i have been reading a lot about ESP8266 and i have found various data for single pin power draw, anywhere from 10mA to 100mA. Also for the 5V pin, some said its about 1A and others said that 5V pin is directly connected to 5V microusb input, which would mean it can suply as much current as the power suply powering the board is able to suply, which in my case would be like 20A (which i am sure would melt the board .. ). Also the board total mA capability would be great to know .. i only use 2 LEDs now but in future i might need to operate 10 LEDs
edit: i see that i am adding to the confusion when i say ESP8266 ... when i say ESP8266, i really mean the ESP8266 d1 wemos board and not the ESP8266 chip itself. And when i say pin, i mean the physical pin to which i attach the sensors and leds, not the pin on the chip itself. I hope this will clear some things up