fire wall clearances, Vent to wall of roof fire wall.

Weezbo

are there specific clearences from a wall that sections one occupancy from the other ,....with a 3 " drainage vent?

then the thing that i wonder is, if the walls have two hour seperations to the sheating on the roof...ought these walls not carry a foot over the roof line?

if so, then is there a minimum horizontal distance from that wall that a vent may inhabit?

any help ?