Sounds good... Very nice project you've made 
About the connection, don't you need any voltage converter for the different lines? Aren't the display running on 3.3V!
I have a display with voltage booster for the backlight too - Color LCD - Breakout Board - LCD-08600 - SparkFun Electronics
About the backlight color, you can use (change, as it's already in the code) this code line.
nokiaLcd.lcd_clear(BLACK,0,0,131,131);
The lcd_clear command just makes a square box with the color,x1,x2,y1,y2 parameters! I hope you understand that 
Also, I can see that you don't know what the "itoa" command is.
It's a integer to string command, which converts a integer to a string so it can be used as a char* parameter.
There is also the "atoi" command, which converts a string (char*) with numbers into a integer value.
Sprintf can do the same as both of them, but it use 1.5K of code, while theese only use a couple of bytes