I've been finding that Spotlight just crashes instantly, no matter what the input after 1-2 seconds. Im getting an error the preference file com.apple.safari.history quit unexpectedly. I can still use it however, if you re-open and try again a couple times.
Spotlight, Immediate crash
It sounds like your system would benefit from updating to the GM (based on your other thread) as that is a full installer and should rectify the issues you're reporting.
-Max.
Did updating to the GM fix these issues for you?