A theatrical wall is called a "flat". There are three primary types of flats. They are as follows:
Hollywood Flat - A flat where the framing is on edge, making it a wider and sturdier flat. Has a hard skin on it. Great for sturdy, fairly permanent walls - not advisable for flats that need to fly in or out.
Soft Broadway Flat - A flat where the framing is on face, making it a thinner, less sturdy flat. Has a fabric skin on it (usually muslin). Easily paintable and very light weight. Great for flats that fly in and out and do not need to hold weight.
Hard Broadway Flat - A flat where the framing is on face, but the skin is a thin plywood, rather than fabric. Still great for flats that fly in and out - can support a bit of weight if you need to dress it with props, etc.
The word is "fourth wall". It refers to the imaginary barrier between the performers and the audience in a theatrical production.
A smal wall
A smal wall
The inner wall is the "endocardium"
I believe that you call it a curtain facade wall or just facade wall.
In general you can call such persons actors.
The Hole in the Wall...the Great Wall that is
They called the Berlin Wall "The Wall of Shame."
The theatrical release of the Movie "WALL-E" has the approx. running time of 98 minutes. (Source Wikipedia and IMDB)
art
A mason
"wall clock" is "horloge murale" in French.