OS X V10.6 Snow Leopard :: How To Remove IWork 06 And 08

I am running the latest version of Snow Leopard on a 2006/7 MacBook Pro. After teaching myself how to use a mac, and how to maintain it, I wish to God I could go back and do full, clean installs of each OS upgrade...alas, hindsight is always 20/20. But thats for another time. My immediate issue is disk space: Using Space Gremlin & browsing my HD I realized I have 3 massive iwork libraries/files/folders. iwork '06, '08, '09. Im certain I dont require all 3 considering I only use most current version (however the previous two take up gigabytes of space). Is there a safe way to delete them? Will the papers written, work saved from '06-on still be able to be opened using the most current version? If so, I wonder why Apple doesnt just delete the old version each time you upgrade?

I have also deleted all podcasts and photos after moving them to an external, yet Im certain that theres gotta be a way to 1) combine my itunes libraries from my two user accounts (I used the same login on both), but have had issues combining songs on my most used account so I can delete the other library for space. After accomplishing that feat I would then like to learn a method to run my itunes and iphoto libraries from my external HD; if so, could someone please help me learn how to do so seamlessly?

Info:
MacBook Pro 15in & iPOD Touch 4G, Mac OS X (10.6.7), 2.16 GHz Intel Core 2 Duo 2 GB 667 MHz DDR2 SDRAM