its vac when engine is running under vac and boost when under boost
fuel pressure reg line is critical. i would not share it with anything else. if you get a leaky hose you will get a lean out and smoke a piston.
bottom pipes are water lines, maybe to stop icing? not a prob over here
this is a link to the nissan parts book for a CA. it will show where all the std lines go
dazza

http://web2.impactblue.org/content/di ... artsdb&action=sectionlist