Well, #3 is pretty easy to answer.

# given the string value in $_ ...

my @v = split m#/#;
unshift @v, shift(@v) =~ /^(.*?)(\d*)$/;
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For values that don't have any letters at the beginning, the first element of @v will be an empty string.

From there, you can easily create a sort key, using (for example)

    sprintf "%-4s%3d%3d%3d", @v;
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Putting it all together:

  map { $_->[1] }
  sort { $_->[0] cmp $_->[1] }
  map {
    my @v = split m#/#;
    unshift @v, shift(@v) =~ /^(.*?)(\d*)$/;
    no warnings; # in case @v has less than 4 elements
    [ sprintf( "%-4s%3d%3d%3d", @v ), $_ ]
  }
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It's probably worth pointing that this could be further optimized by using the GRT, or possibly fast, flexible, stable sort. See also this tutorial on sorting.