for the on off vs high low I would need to check in detail.
However for the inverted function, that is pretty much normal and depends how the LED is connected to the ESP. The ESP could basically apply 3.3V to the LED circuit via its GPIO pin. Then on really means on. However often, 3.3 V are applied externally to the LED circuit and the GPIO is used to define Ground. In this case the LED is on if the GPIO is set to low resp. off.
The ESP is still a port with work in progress, but many use it since it comes so dirt cheap.
Don't be afraid... the forum is helpfull
