I have a couple fireblocking questions:

1.  if i have a opening in the floor plate to allow hvac to go through, but have 2×4 blocking above it and the wall is covered with drywall, is that appropriate fireblocking?  if so, is there a distance above the floor plate that would be required where you install the 2×4?  I have two 2×4 blocks at 27″ above, and another one above that.  i’ve attached a pic showing the blocking.  the area in the floor plate with the hole is on the bottom left side of the hvac, which i’ve stuffed with some mineral wool insulation.  

2.  I have a drain cutout in my subfloor that goes all the way from the basement to the 2nd floor (an attached pic shows the dwv pipe going through the opening).  in the recent article on finehomebuilding about fireblocking, it indicates:

“Drain cutouts for drop-in tubs and showers can leave interconnections between the enclosure walls and floor system below. It’s best addressed at the drain, but blocking around the rim is often acceptable.”

Now, when i bought the house there were obvious and multiple penetrations in the ceiling from the basement into the subfloor above.  these were obvious since basement was unfinished.  should the inspector have flagged each of these as against code since they did not have fire-rated caulk or other approved fire blocking material covering up the holes?  or, is the goal of fireblocking to keep the fire from moving swiftly in the stud bay.  To me, perhaps that explains the part in the above quote that states “but blocking around the rim is often acceptable”. 

I did put down 23/32″ subfloor.

Thank you.