<img src="enc28j60.png" width-500px />
1) SPI interfece.
2) SPI pins MOSI, MISO, SCK cannot be changed. They are hardware configured in arduino. For details about SPI configuration for different boards, check here
3) To find the Slave Select (SS) pin, check the library. There are two libraries implemented for this module
a) EtherCard, SS PIN : 8
b) UIPEthernet, SS PIN 10. This library uses an API which is compatable with the official arduino Ethernet library for ethernet shields. You can use the examples of the official library just by changing the header file from Ethernet to UIPEthernet
The pin configurations for UPIEthernet are defined in the file utility/Enc28J60Network.h
But this library uses almost 15% more flash memory( out of 32K) and almost 50% more SRAM memory (out of 2K). Hence its better to use this module with arduino mega