Directly dealing with the SPI controller in the AVR is sort of beyond the scope of the Arduino environment, so I'm not sure there is an "arduino style" to follow. The symbols you're looking for (SPE, MSTR, etc) are defined in an include file <avr/iom8.h> or <avr/iom16.h>, which the Arduino environment already includes for you at the beginning of the sketch, and when I copied the code segment you mentioned into the setup() of the led_blink example, it worked fine.
For the meanings of the symbols, you'll need to look in the Atmel data sheets for the parts:
http://www.avrfreaks.net/index.php?module=Freaks%20Files&func=viewFile&id=1242&showinfo=1