Mass air flow is the chunk of aluminum that is attached to your stock airbox. It has a connector harness pluged into it. It meters the incoming intake airflow.
Vacuum hoses are all over the place. Pull off a hose, if it sucks <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='
'>, then its vacuum.