I found three ways to get real-time changed folder alerts:
  1. A folder action (that was easily implementable through either Mavericks or Yosemite but no longer is)
  2. An Automator workflow (Automator confuses the hell out of me!)
  3. A shell script (that looked more daunting than it probably actually was)
But while I was deciding which way to go - I had already decided that joemike's suggestion that I reinstall OS X was overkill, but Archive & Install lives? revived it as a possibility. - and thinking about what help I might need to get there the crashes slowed down to a trickle.

And since I now haven't experienced a crash in more than 36 hours, and a new version of Safari has been released, I'm back in a holding pattern until I see what happens with Safari 10.0.1.

As I've said, though, in this instance, troubleshooting may be more trouble than the trouble, itself.

New info that I found in the crash report:

Code:
Dyld Error Message:
  Symbol not found: _OBJC_CLASS_$_FirstLogInHelper
  Referenced from: /System/Library/PrivateFrameworks/SafariServices.framework/Versions/A/XPCServices/com.apple.SafariServices.xpc/Contents/MacOS/com.apple.SafariServices
  Expected in: /System/Library/StagedFrameworks/Safari/Safari.framework/Versions/A/Safari
 in /System/Library/PrivateFrameworks/SafariServices.framework/Versions/A/XPCServices/com.apple.SafariServices.xpc/Contents/MacOS/com.apple.SafariServices

That somehow sounds like a wonky Safari installation?

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire