<...>What I find rather amusing is that in this case, the USB has no real functionality other than programming and testing it since the device is primarily a WiFi terminal and the computer to which you connect the USB almost certainly itself has wither wired Ethernet or Wi-Fi capability (or both), so the ESP as such really cannot add functionality to the PC either in connectivity or processing power (not that its processing power is insubstantial).
Compiled under Arduino 1.6.8 Sketch uses 232,782 bytes (22%) of program storage space. Maximum is 1,044,464 bytes. Global variables use 31,995 bytes (39%) of dynamic memory, leaving 49,925 bytes for local variables. Maximum is 81,920 bytes.