My comments:

• You're defining the subroutine to take no arguments (the empty parens after the sub name are the prototype for no args) yet you are apparently expecting args:

  sub readDRC ( ) {
  my ( $file  , $flag ) = @_ ;
  [download]

  This leads me to believe that you probably don't understand perl's "protoypes", so you probably shouldn't use them.
• You're not checking the return value of your open()
• Your C-style for loop is very non-idiomatic. When looping over an array like that, it typically looks like this: for (my $i = 0; $i < @array; $i++) { ... }
• And also relating to the for loop, it looks like you really want the Perl-style for loop:

  for my $item (@drc::file) {
     if ($item =~ m/^\s*\Module:/i ) { $moduleName = getModuleName($item
  +); }
     ...
  }
  [download]

• And as to why you're not getting the values out that you put in, make sure that that all of your keys have the values you think they do. If you don't have warnings and strict on, turn them on. Perhaps you typoed a variable name or something. Sorry I can't be more help on that.
• As for passing hashes to subroutines, you do it the same way you are passing your arrays (i.e. you pass a reference to your hashes)