Your summary is correct, except for the following comment:

This thickness [...] is seen from lower levels with the color or texture that is used for the floor of the corresponding room when looking up from lower floors.

The color or texture seen from lower levels is rather the color or texture set for the ceiling of the rooms at the lower level, as you explain it in the 3rd point. Actually, you comment is true only if there's no room at the lower level.
See also the Managing the ceiling at first floor section in this tip.