New functions for buildings

[Kirid]

While modding buildings, I've came across some ideas to expand their functionality.

1. Buildings that can intersect/be built on others.
         Ability to control exactly what they can or cant build over.
        (Floor Rugs)(Ceiling lights, build over anything except walls)

2. The ability to define different parts of an building as passable or impassable.
        You could define the whole item as impassable, then define what spots should be passable, or visa versa.
       (Turrets that colonists get into)(Complicated workshop shapes)

3. Buildings that can have different faces determined, like pawns currently have.
          Would help making complex graphics rotatable.

4. Ability to make colonists interact with building when happiness is low, or when idle.
       More important: Control, so they dont dart for such items when their happiness hits a certain low.

^edit5. Building definition so pawns can walk underneath.
         (Ceiling and wall lights, This and #2 = walk behind cacti?)

Not sure if these are doable at all, or If the core game needs them. Having the ability available for modders if anything.
Would be awesome if they are possible already, Can overdraw do something like this? Sorry if these ideas aren't new, I know #4 isnt.