Strange Build #. Want to root, backup and revert.

I need a bit of help with this one.

I have a Samsung Galaxy S4 on Verizon, Android 4.4.2 Build VRUFNK4 (I believe this is an intermediate build between the stock VRUFNK1 and Lollipop).

What I'd like to do is root, backup the current build and then revert back if possible to VRUFNK1.

I'm new to rooting a phone so I could use a bit of help and links. I've read many of the posts and tips, but most specifically don't mention my build, which makes me a bit nervous.

Will towelroot work with this ?
Should I use TWRP or Titanium for backup ?
And.........can I find and revert back to the official build VRUFNK1 (4.4.2)

I simply want to get out of this strange build, remove bloatware........ and have some control over not being pestered over OTA updates from Verizon/Samsung.
Possibly, in the future, I'll play around with some custom ROM's.

Any help and opinions would be appreciated.

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