> The item hanging on the left-hand wall has me completely flummoxed.

A tool known by many names, one that is essential for making casks in
tight cooperage (making vessels that don't permit the passage of 
liquids).
I've given up on finding THE name, and use the French, "batissoir."

> Is the metal plate on the lower-central cheek a blade? If not, what?

It's simply a reinforcement or perhaps a repair for the threaded hole
in that piece.

> I don't see what this would do for a cooper.

After the staves have been shaped, they are still straight boards. They
are gathered into a truss hoop, followed by three or four more truss
hoops which are driven down, pinching the staves together.  At this 
point
they look like a skirt, gathered at the top and flaring out at the 
bottom.

To turn them into a barrel, they are heated with fire until the wood is
at about 200 degrees.  At this point the batissoir is used, like a sort 
of
giant hose clamp to draw in the staves at the bottom, creating the curve
of the barrel, and more truss hoops are driven over that end.

The process is shown on this video at about 2 minutes 40 seconds:

https://www.youtube.com/wa
tch?v=027bBKuhLWw

There was a much better video, actually a couple of them, but they are
no longer on Utube.

Mike in Sacto