Excellent post - I was where you are now, 3 years ago.
You may find this document at IFI Robotics interesting
Control System Overview.
Over at Microchip you will find detailed (!) programming reference materials for the PIC
PIC18F8722 resources.
If you don't want to climb the detailed learning curve of itsy-bitsy details, I suggest looking at Easy/C (there is a 30-day eval) and the accompanying WPILIB library.