questions about the PS backend


currently I am having a closer look at the PostScript backend.
Some questions occurred to me:

1) What is the meaning of 'backend_version'? When should it
  be increased/changed?

2) Is the following code the correct way to get the
  matplotlib version for use in a backend file:

    from matplotlib import __version__

3) The draw_lines method checks whether the argument arrays
  are of the same size as required. The other functions do not
  do any sanity checks on the arguments. Can the renderer methods
  assume that they are called with semantically correct arguments?
  Is it ok to fail with an Python exception otherwise?

4) Can the PostScript code assume that each file contains only one
  picture/page? Might this change in the future?

5) Does matplotlib have the concept of a picture title which could
  be written into the DSC "%%Title" comment? If the answer is yes:
  how do I get this title?

Also I have some questions about the template backend in

6) The template backend contains the line

    from matplotlib.transforms import Bbox

   Does this have any function or should it be removed?

7) The template backend uses'Error: %s'%msg)

   Should this be 'verbose.report_error' instead?

Sorry about having so many questions,