Does anyone know what the logic for the E reading are
Are they just a running accumulation or do they get clear and if so when.
Something else that is new is the Control feature, what is this for and how does it work.
I could not find any documentation on these 
Interesting point for @TrystanLea. No the docs don’t tell you a definition of what the data sent is. That looks like an output from a Wi-Fi module.
You should see the E (Energy) increasing.
Don’t know. 
They are the energy values in Wh and accumulate indefinitely. However, although the values are stored in EEPROM, they are only updated when the value has changed by a significant amount in order to minimise wear on the EEPROM - 200 Wh as I wrote the original library, but I understand it has been changed by others since. Therefore, if the sketch is restarted for any reason, there might be a small loss - not greater than 200 Wh.
The Control feature is not part of the emonTx4, but belongs to the ESP8266. I don’t know what it does either.
The control feature was for use when the EmonESP code was used on the WiFi relay or Sonoff S20 smartplugs. It’s otherwise unused, it will just be toggling a digital pin on the WiFi board.
Should this not be documented somewhere in order to avoid further confusion?
Yes 
