I think it's still a little unclear about Rosetta and also Java for people upgrading, but your best bet would be to find someone running one of the developer preview releases.
There's basically two ways it could go.
1: Both Rosetta and Java are grandfathered in, meaning that the installer doesn't remove them, but they're no longer maintained and could potentially stop working with any subsequent update due to changes made.
2: The installer removes both of them and there's no option to reinstall
As for whether or not Pages or Word or even LibreOffice/OpenOffice Writer will open these old files probably depends on just how old they are. AppleWorks went away a LONG time ago. iWorks came out around 2004-2005 if memory serves, and I believe AppleWorks had been abandoned long before that. If I'm thinking of the right program, it was an old OS Classic program, that Apple did a minimal port of for OS X, and stopped including with new systems about the time they stopped installing OS 9 in a dual boot config. You'll have to check which file types Pages, Word and Writer will open, and probably want to make sure you have all three on your system to figure out which one works best. You may also want to check to see if AppleWorks offers any other format options for saving. If you can get it into a reasonably modern format, such as Office 97-2003, then you shouldn't have much difficulty opening it in any of those three programs.
Just as a general rule though, you need to stop clinging to old software for so long. At some point the pragmatism of ensuring that you can continue to use these files indefinitely needs to outweigh the stubborn and/or cheap part of you that says what you have is working fine. Some degree of that is admirable, but you have to balance it with the fact that the rest of the world is moving on, and your computer won't last forever. Even solid state components eventually fail. Skipping one, maybe two versions isn't a huge deal, but once you go beyond that you're asking for trouble.
I have read that Lion will not support Rosetta and that AppleWorks - that neat clean office suite will no longer be functional. I just bought a new 27" iMac running Snow Leopard. If I continue to use AppleWorks on this and open Rosetta to do so, when I upgrade to Lion, will I be able to
1. remove Rosetta or will it automatically be removed?
2. still be able to open the old AppleWorks documents by File>Open With>Pages or Microsoft Office?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic