Keyboard Control Not Working As Intended
The problem I see is that your servo is attached to pin 0.

Pins 0 and 1 are used by arduino unos and megas for serial communication, so you can't output to a motor and send/receive serial at the same time. Try moving the servo to pin 3 and see what happens.

In response to your comment, any character sent from any terminal (or other piece of hardware) will work; you do not need to use Processing to communicate with an arduino.