How to convert a pdf file from gray-scale to black-white

You are already using Ghostscript in ps2pdf, so this answer would do it:

gswin32c.exe 
-o c:/path/to/output-cmyk.pdf 
-sDEVICE=pdfwrite 
-dUseCIEColor 
-sProcessColorModel=DeviceCMYK 
-sColorConversionStrategy=CMYK 
-sColorConversionStrategyForImages=CMYK 
 input-rgb.pdf

If you have a relatively simple file tree where you have only one level of directories, and where each directory contains a list of files but there are no sub directories, you should be able to do something like this (you can paste this directly into your terminal and hit Enter):

for dir in *; do    ## For each directory
 if [ "$(ls -A "$dir")" ]; then  ## If the dir is not empty
   for file in "$dir"/*; do      ## For each file in $dir
    i=0;                         ## initialize a counter
    ## Get the subject
    sub=$(grep ^Subject: "$file" | cut -d ':' -f 2-);
    ## get the date, and format it to MMDDYY_Hour:Min:Sec
    date=$(date -d "$(grep ^Date: $file | cut -d ':' -f 2-)" +%m%d%y_%H:%M:%S);
    ## the pdf's name will be <directory's name> _ <date> _ <subject>
    name="$dir"_"$date"_"$sub";
    ## if a file of this name exists
    while [ -e "$dir/$name".pdf ]; do
      let i++;                       ## increment the counter
      name="$dir"_"$date"_"$sub"$i;  ## append it to the pdf's name
    done;
    wkhtmltopdf "$file" "$dir"/"$name".pdf; ## convert html to pdf
  done
 fi
done

NOTES

• This solution requires wkhtmltopdf:

  Simple shell utility to convert html to pdf using the webkit rendering engine, and qt.

  On Debian based systems you can install it with

  sudo apt-get install wkhtmltopdf
  

• It assumes there are no files in the top level directory and only desired html files in all sub directories.

• It can deal with file and directory names that contain spaces, new lines and other unorthodox characters.

• Given a file dir1/foo with the contents of the example you have posted, it will create a file called dir1/dir1_020513_20:59:53_Civilized Discourse Construction Kit10.pdf