OK, well :fit_window_to_text is not the option you seem to want. What that option means is that if you have only short lines, the window will shrink to accomodate. In other words, it changes the window size.
The option it sounds like you are looking for is :paragraph_format, which will fit the text to the window - ie. if the text goes over, it will go to the next line.
For faces, you just need to change the :face_width and :face_height options. If you change them both to 0, then it will always show the whole face. Otherwise, it will cut the image out of the centre of the picture to the values specified.
Have you played through the demo? The guy with purple hair talks about faces, and the guy with red hair explains paragraph formatting.