Even if you uninstall 0.9.2, your settings are still retained. However, if you have extensions installed and you've customized them, you may want to find their .rdf files and save a copy of those. They'll be under Windows->Application Data->Mozilla->Firefox->Profiles->[profle_name].glg in Win98.
I believe the various versions of 0.9 can be reinstalled over one another. In fact I think the goal is for all future versions of FireFox to be upgradable that way. Personally, I prefer fresh installs anyway; makes it easier to compare and see about new or missing features.