Colors and windows programming

I started reading about colors (Graphics chapter)  in pdf reference.

In windows (.NET) when we draw some color we use only the RGB format.

If I want to display a filled rectangle in the screen I use this code.

 gr.FillRectangle(Color.FromArgb(r, g, b), rect);

I dont modify the code  if I want to print it. Windows api (I think) takes care that the color will be the same in monitor and paper.

1 If I write a program that reads pdf should I transform the document colors to RGB?

2 Will the values of RGB be the same for displaing to the screen and printing?

Thank You