1 point" Multiple libraries were found for..." You've got a configuration error message. Time to read the docs on porting from other libraries. How-To: Porting Libraries Posting a Library for Energia Some Misconceptions about Libraries The above may provide guidance. I am not able to help much beyond this suggestion as I'm deeply involved in other non-coding projects at this time.
1 pointHI ! No MQTT with AT commands on ESP6266 IMHO !! (among the several AT firmwares I know) You can use Arduino IDE (+ ESP8266 core) to flash your ESP-01 with your own application receiving data through UART and publishing data to an MQTT broker (use pubsub library) (WEMOS D1 mini is a good alternative to ESP-01 with it's good 3V3 regulator, some passive components, USB interface for easy developping...)