Hi Zach,
Sorry for the belated reply!
Standard ESCs, including the basic ESC, are controlled by PWM signals, which range from 1100μs to 1900μs for full reverse to full forward in the case of the BasicESC, with neutral at 1500μs. If you would like to very precisely control the speed, then you need to precisely generate PWM signals, which is easy to do with an Arduino board. A simple Arduino program based on our example code will let you change the throttle value easily with a computer.
You cannot receive any telemetry information back through the PWM line, but you can do so and also control the ESC via I2C. The BasicESC should be able to report RPM and voltage information, though I2C on the BasicESC is a “hackable” feature. The pads are under the heat shrink, so you will need to cut that off and load a modified firmware for I2C operation. You can see this forum post for more information, and these instructions for how to flash the required modified firmware file.
-Adam