Welcome to PS Gurus, Karin, and to the Mac! And I love your work!
First, the PS filters problem: I assume you mean the filters that ship with Photoshop? Liquefy (among others)
should show up under your Filters menu (where it belongs; in PS 6 it was under the Image menu). If you're talking about 3rd party filters, some of them aren't yet Carbonized for OS X, and won't show up when running PS in OS X. Run PS in Classic mode to check, then check with the filter's creator site.
As you've reinstalled PS, the problem isn't the preferences file which is a common fix. But, when you reinstalled, did you trash the original first? If you didn't, any installer problems you had before will simply be recreated.
First, trash the application itself. Depending on where you installed it, drag the folder to the Trash. It's probably in your Applications folder.
Second, trash the Preferences file. this lives in Users:[user profile]:Library

references:Adobe Photoshop 7.0 Settings.
You're now ready to reinstall, and you'll have a fresh copy.
More troubleshooting:
Check Adobe's site for PS updates. The latest for Mac is 7.01 which you can get
here.
Check what version of OS X you're running. (Apple Menu > About This Mac). Make sure you have the latest in Sofware Update. To run PS 7 properly in OS X, you need version 10.1.3 or later.
Log out. It's not often, but sometimes OS X needs a "kick start" and logging out and back in will do that. (Apple Menu > Log out). Then log in again.
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As for your printing problem, there are "known issues" (i.e. bugs) with certain Epson printers and OS X 10.2.1. The fix (this works for some Epson printers, but it's worth a try and won't hurt anything) :
- Remove your current Epson from the Print Center list (don't trash it!)
- Insert your Jaguar CD disk 2 and install the Epson driver package.
- Add your original Epson 925 from Print Center.
Good luck! If you have any other problems, or further questions, don't hesitate to ask.