I'm not sure, as dvergin also mentioned, that I understand what 4) is about. But I'll try a generalized answer that may help. I find that I seldom use the / / argument of the split command. The  split " ", $var is much more useful. Notice in the following example that it strips out multiple instances of whitespace (from the beginning of the string as well):

use strict;
my @lines = <DATA>;
chomp @lines;
foreach (@lines) {
   my @words = split " ", $_;
   print "\$_: '$_'\n";
   foreach (@words) {
      print "'$_' ";
   }
   print "\n\n";
}
__DATA__
 Delimit each  word with   one  or more spaces
   This  is  the    second  line
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Output:

$_: ' Delimit each  word with   one  or more spaces'
'Delimit' 'each' 'word' 'with' 'one' 'or' 'more' 'spaces' 

$_: '   This  is  the    second  line'
'This' 'is' 'the' 'second' 'line'
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Note also that the following shorter version for the above will work also:

   my @words = split;
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--Jim