Can you point out some actions i may want to take to fix problem im having.
It is not a "problem" at all. You were warned only that UART2 has no valid pin mapping. I guess, that you don't need it at all, so you don't have to do anything.
Maybe it is a better choice to rewrite this code to use a c30 own library files.
There are several choices:
1. You can use the PIC24 support libraries downloaded from www.reesemicro.com
2. Since the lcd4bit.c is a quite self-containing code (from the point of view of handling the LCD), you can rewrite it to a code which doesn't use _any_ library. (Of course, you should provide the clock setup code and few delay routines).
3. It is also possible to use the "factory" C30 library functions (OpenXLCD, BusyXLCD, PutsXLCD,etc.).
1-How universal are the routines for char LCDs (Different PIC series...)
Theoretically it can be witten in a portable way, but who care it?
2-Can i use very simple LCD initializing program for a complex project... ?
3-Iv seen a LCD source code with print function, WOW :D really nice. Do i really need it ?
You may need it if you make complex formatting or conversion.
4-Iv tried to display something on LCD... nothing shows up. If contrast pin is equal to a LCD voltage is it OK ?
Not at all. It should be somewhere near to ground (in my case the data sheet says tha Vdd= 5 V, VO= Vdd-4.4 V, so VO is about 0.6V)
5-If ill try to write a LCD initializing code by myself instead of using sample. Will it benefit ?
You may have different intention (say need blinking cursor, special characters) which may be a good reason to change the sample code. You may also want to reset the LCD in special cases, which is missing from the usual example programs).
6-Is there a useful tutorial You know, ebook maybe... i could use. HD44780 datasheet On-line LCD simulator tutorial part 1. tutorial part 2.
7-What is the difference between 8 bit and 4 bit data interface ? How complicated is the in code configuration ?
The 4-bit mode moves data in a half byte pieces. It requres fewer pins, bits and wires, but more time.
8-Any problems i may face later?
Who knows the future? :-)