What happened with Gidget, Sara Lee, Daisy and Zim?

Besides losing their original bassist and keyboardist, MM have had at least four other personnel changes.

Second bassist Gidget Gein (known to have had a heroin habit) left the band in December 1993, during the last stages of the re-recording of POAAF. Mr. Manson stated that "he felt that his drug addiction was more important than playing bass for us." He has since emphasized that the problem was Gein's loss of control over his habit, not his heroin use as such.
--Drummer Sara Lee Lucas left the band in March 1995 after an incident in which Manson set his drum kit afire onstage. Manson has since added that Lucas couldn't "keep up with the click in his headset" - i.e., couldn't keep time.
As for Daisy Berkowitz, the split between him and MM seems to be mostly due to creative differences in regards to the direction and content of "Antichrist Superstar". Daisy (now known as Scott Mitchell) has filed a lawsuit against Manson and his lawyers, citing various infractions; the matter is currently in the hands of the American legal system.
With Zim Zum, his exit is a little more clouded-- at this writing it's not clear if this latest shake up in the membership is amicable or not, but Zim is currently maintaining a very positive spin on the whole thing, and emphasizing his desires to work with other people and to do his own music rather than tour for the next year and a half.