I recently got a drop clutch for my hh and it's great(http://www.musiciansfriend.com/srs7/sid=030130232612140146215162044996/search/g=home?q=drop+clutch).  

There's a problem I've had where the bottom bolt(underneath the top cymbal) keeps unscrewing slowly but surely.  Is there a way to stop the bolt from unscrewing itself or is this natural?

Go to the hardware store and buy the nut with the setscrew OR buy a bit, tap, and do it yourself.

i have the dw clutch too but i've ever had to lock it.