How to replace:
From the pic (not the spin on filter) at this site it looks like you open the Drain bolt on bottom of the filter and drain out the old Fuel into a suitable container and close the plug back on.
You remove the central bolt and remove the cover to gain access to the Fuel Filter Element. Yank out the old filter and put in the new one. Put on the new gaskets/O-rings as needed. Install new filter and fill canister with clean Diesel Fuel (or prepare to do a lot of pumping with the hand primer). Put the Filter Housing Lid back on with the proper gaskets/O-rings and the Central bolt tight.
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=123130&M=617%2E912&GA=722%2E118405&GM=716%2E005++++++++++++++717%2E400&CT=M&cat=143&SID=07&SGR=120&SGN=04
The Fuel Supply Pump is item #305 and the thing sticking up from the supply pump is the Hand Primer.
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=123130&M=617%2E912&GA=722%2E118405&GM=716%2E005++++++++++++++717%2E400&CT=M&cat=143&SID=07&SGR=045&SGN=01