Hello Zedy
You should tell the HiTech compiler which pic you're using...
#include <htc.h> // Required to interface with delay routines
#include <pic12f683.h> //modify this with your pic
And be careful when using lcd_port, because you're actually modifying the 8 bits of the port at the same time... including RC4 and RC5, which should not be changed.
I'd recommend using that LCD on a 4bit mode and whenever you want to send a 4 bit command or data, be sure not to modify the other RCx pins.
In order to do that you'll have to use AND, OR or XOR masks.
Ohh and there is a pre-built LCD library with Hitech, just search for it in the installation paths.