1st question:
In any case, the black bar would rise higher than 1.5 levels because of the stairwell symbol of the adjacent hex M16. So no LOS.
2nd question:
"B23.71 ROWHOUSE: Any multihex building with a thick black bar over any hexside it crosses (such as 23K7) is considered a Rowhouse structure composed of separate Rowhouses. As a multihex building, Rowhouses have an upper level(s) and are considered either 1½ level obstacles to LOS if they have only an inherent stairwell (23.22) such as 20X6, or 2½ level obstacles if they have a printed stairwell (23.23) such as 12O4. The thick black bar blocks all LOS through it at all levels [EXC: Rowhouse rooftop units retain their normal LOS]. Rubble has no effect on this black bar unless both hexes formed by that hexside are rubbled, in which case it ceases to exist. Infantry in a Rowhouse may move/rout/advance/Withdraw-from-CC directly into another Rowhouse hex of the same building only at the ground or Rooftop (23.8) level; if at the ground level they must specify which side of the building they are "bypassing". Such units moving/routing on the ground level expend three MF (one to "bypass" in the hex it is leaving where it would be attacked by any OBA/Residual-FP and two to enter the building), and can be Interdicted or Defensive First Fired upon with FFMO/FFNAM DRM by any unit capable of doing so that can trace a LOS to the vertex of the hexside crossed by the moving/routing unit on that side of the building. If broken, pinned, or repulsed at this vertex, the unit is returned to its last-occupied Location as if it had attempted to enter a concealed MMC's Location during its MPh (A12.15). A ground-level move/rout/advance/Withdrawal of this type is vulnerable to any mines in either hex. Units in different Rowhouses may not form a FG unless each is ADJACENT to another unit that is not in a Rowhouse but that is part of that FG. Each hex of a Rowhouse building is always considered a separate building for Rout and Mopping Up purposes but not for Building Control."
So in your case, LOS is blocked by the black bar.
von Marwitz