The reason that they made string shot lower by two stages is because bug type pokemon were starting to become very weak pokemon at the beginning of the game, so in order to change that, they made modifications to some of the bug type moves. Like, before, Fury Cutter used to do 10 damage and increase towards 160, but now it increases to 160 by increasing with a base power of 40. Here's a link if you wanted to check it out:
http://pokemondb.net/move/fury-cutter
As for the Whirlwind, you're either right about the roar copy-paste error, or the company decided that it's not really a move that is related to sound.