[Groff] tbl footnotes and graph position

[James K. Lowden]

http://www.schemamania.org/tbl/eg/t.pdf
http://www.schemamania.org/tbl/eg/t.ms

After a week trying out groff, I have three questions about the above
tables.  I hope someone can steer me in the right direction.  

1.  Why is the last column in both tables so wide?  tbl columns can set
a minimum width, but I don't see how to encourage tbl to make one
particular column narrower.  

2.  The last two rows in the first table are too tall.  I think it's
the footnotes, but I don't understand why.  AIUI tbl calls groff to
render what lies in T{ ... T}, and surely groff isn't telling tbl it
needs all that vertical space.   

In groff's defense, I am ignoring these warnings

<standard input>:72: warning [p 1, 0.7i, div `3tbd39,0', 0.0i]: 
        cannot adjust line 
<standard input>:72: warning [p 1, 0.7i, div `3tbd39,0', 0.1i]: 
        cannot adjust line 
<standard input>:80: warning [p 1, 0.7i, div `3tbd40,0', 0.0i]: 
        cannot adjust line

mostly because I don't understand anything after the word "warning".  

3.  This report is to be two columns; the right column holds graph.
When I added the .2C macro, the display after the 2nd table suddenly
jumped to the top of the second column.  I had to reduce the top and
bottom margins to get the formatter to include it in the first column.
How might I tell groff to keep the display in column 1?  In effect, I
want the display to be "attached" to the second table.  

I think I know why .2C had that effect: as soon as I said ".2C" the
formatter saw it had half of Nebraska to work with and decided to use
it.  I'm looking for a way to explain that, no, that other column is
reserved. No combination of .RC or .br dissuaded it.  

I also tried to position the graph without .2C, simply by using 

        .G1
         pic move to (4,-4)

when starting the graph, but no graph appeared.  Is that a sound
choice?  The manual seems to say it should work:

        "If no plotting commands have been given before the frame
command is issued, the frame will be output at  that  point  in  the
plotting stream  relative  to embedded troff or pic commands.
Otherwise the frame is output before the first  plotted  object  (even
invisible ones)."

Many thanks for your kind advice.  

--jkl