Mail, Chrome, Safari & others crash after OSX 10.9.4 update

Question

I'm on a 27-inch, late 2012 iMac (intel), and after updating to 10.9.4 a number of my apps will not open - the icon bounces on the doc and then stops bouncing without ever opening.  Apps include Mail, Chrome, Safari no longer work.  What's worse is the Crash Reporter also crashes, so I never see a report.
I downloaded the OSX Updater Combo to see if I could re-run the installer, but the installer app does the same!
When running in Safe Mode, everything still crashes, but at least then the Crash Reporter doesn't crash.
I ran a diagnostics based on the instructions from this thread (Safari, System preferences and Chrome quits unexpectedly), and have pasted the response here:
http://pastebin.com/aCBRZ371
Between that and from the Crash Reporter was saying when in Safe Mode, it looks like it has to do with the Webkit engine, something about a WebCore framework? This is beyond my depths.
The App Store app will start up, but nothing ever displays. Between that and the installer app crashing, I feel like I may be dead in the water.  Any help would be hugely appreciated.

Answer 1

A.
Some of your user files (not system files) have incorrect permissions or are locked. This procedure will unlock those files and reset their ownership, permissions, and access controls to the default. If you've intentionally set special values for those attributes, they will be reverted. In that case, either stop here, or be prepared to recreate the settings if necessary. Do so only after verifying that those settings didn't cause the problem. If none of this is meaningful to you, you don't need to worry about it, but you do need to follow the instructions below.
Back up all data.
Step 1
If you have more than one user, and the one in question is not an administrator, then go to Step 2.
Enter the following command in the Terminal window in the same way as before (triple-click, copy, and paste):
sudo find ~ $TMPDIR.. -exec chflags nouchg,nouappnd {} + -exec chown $UID {} + -exec chmod +rw {} + -exec chmod -N {} + -type d -exec chmod +x {} + 2>&-
This time you'll be prompted for your login password, which won't be displayed when you type it. Type carefully and then press return. You may get a one-time warning to be careful. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.
The command may take several minutes to run, depending on how many files you have. Wait for a new line ending in a dollar sign ($) to appear, then quit Terminal.
Step 2 (optional)
Take this step only if you have trouble with Step 1, if you prefer not to take it, or if it doesn't solve the problem.
Start up in Recovery mode. When the OS X Utilities screen appears, select
          Utilities ▹ Terminal
from the menu bar. A Terminal window will open. In that window, type this:
res
Press the tab key. The partial command you typed will automatically be completed to this:
resetpassword
Press return. A Reset Password window will open. You’re not going to reset a password.
Select your startup volume ("Macintosh HD," unless you gave it a different name) if not already selected.
Select your username from the menu labeled Select the user account if not already selected.
Under Reset Home Directory Permissions and ACLs, click the Reset button
Select
           ▹ Restart
from the menu bar.
B.
Your hosts file is massively hacked. I suggest you unhack it and test.
C.
If you still have problems after taking the above steps, run the following command:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.rpmuxd.plist