I think you can manage Font Collections using the Type window in OSX (the one you call with Command-T in TextEdit). Refer to the OSX Help, it's in there.
Maybe Font Reserve (Enfocus) or FontAgent (Insider Software) can also do this for you.
I still work under OS9 when I have design to do. OSX is mediocre with fonts: there's no Finder preview (that's even WORSE than OS9) for fonts ! Acrobat 5, ATM Deluxe and Adobe Type Reunion make OS9 the perfect PDF platfrom for me, I won't get into OSX. Plus, Quark is OS9 (and I don't want to hear about a OSX only version of it !).
In brief, I'd recommend staying under Classic.