Just to be clear, there is no USB involved. This is a direct serial connection between two microcontrollers, where one microcontroller includes WiFi capability. I went this way to avoid the USB driver, operation system, etc. headaches.
The ESP-12F module I'm using in my VacBot only draws between 80 and 100 amps (other modules may vary).
By the way, there is a cutout for the connector in the bot so that when you remove the front bumper you have direct access to it. I somebody would find a matching connector, there would be no soldering involved. I guess that the connector would be similar to a PCI-type, but just with six pins.
Also again, be careful if you're experimenting with an Arduino. These us 5v signal levels and may damage your 3.3v BotVac
board (ESP8266 also use 3.3v).