Basic rules for buildings are in AS on pages 83-85. Rules for armed and/or armored non-mobile buildings are in ASC on pages 24-26.
Of relevance to my first set of questions is the following rule:
During game play, the armor value for each exposed facing
of an armored building must be tracked separately. As long as
a facing still possesses any armor, unfriendly non-infantry units
cannot enter or pass through the building walls, nor can their
attacks deliver any damage to the armored buildings CF, or to
any units inside. Unfriendly infantry units can attempt to enter an
armored building as if they were boarding an exceptionally large
unit type (see pp. 98-99, AS).
Q1) Should an advanced building always be assumed to have 4 facings of equal size (linked to the 4 cardinal directions of the game table) plus "top" for 5 total facings, or should the number and size of each of a building's facings be determined by the shape of the model itself? (perhaps a pyramid with 3 sides and no top, or a Spherical building having 2 sides of left/right, etc)
I presume the answer to questions 2-5 are "No", but I am looking for confirmation.
Q2) When a unit has LOS to multiple facings of the building, are there any restrictions on which facing an attacking unit may target?
Q3) Are there any additional penalties involved for an attack against a facing that is within LOS but is not the "most directly" prominent facing?
Q4) Are armored walls considered to have a "top" facing?
Q5) If a unit is the target of an attack and is within an armored building that has lost armor on the facing that the attacker's LOS passes through, is that unit still immune to that attack's damage because the building "still has armor" on at least one facing?
The ASC errata doc establishes Advanced Buildings as a distinct entity from Mobile Structures with regards to conversion from TW to AS. However there is still no mention of advanced buildings in the PV conversion rules. You can't really use Mobile Structures rules for PV for buildings; they have way more CF than Mobile Structures have structure and would result in dramatically over-priced buildings in PV.
Q6) Are there any plans to publish rules for assigning PV to armed and/or armored buildings?