Printing combinations of lines from different files

Re: 2 (partially). I would do something like this to create the folder:

if !isdir(outputdir)
  mkdir(outputdir)  # creates the folder in case it doesn't exist
end

function _writetodir()
  # here put the code that writes the file
end

cd(_writetodir, outputdir) # temporarily access to outputdir just to do the writing stuff.

where “outputdir” is a String that contains the full path to the directory where you want the output file to be written.