need more info. Try to install the update and once it reboots and you see the little box unpacking hit both volume buttons at the same time to see what is going on so you can see the error that fails.

I am guessing that you are getting a status 7 error and are missing some apps. If so, read this:
http://forum.xda-developers.com/showthread.php?t=1406550

and use this system dump:
http://androidforums.com/droid-4-all-things-root/501021-droid-4-dump.html

to put the apps back.

It is an iterative process that takes a while because it only tells you one app at a time what is missing and you have to keep going back and re-downloading and installing the update to see what fails next.

wash. rinse. repeat. (until it works)

 

no. you'll need access to the system folder, hence, root. However, you can use rootkeeper to set it back to unrooted temporarily if you are worried about taking it to the verizon store or something.

Having root just gives you more access/permissions. Just because you have it doesn't mean you need to flash a new rom or anything. You can also unroot it I think, but why do it? It comes in handy sometimes.

 

I guess one other option is to take it back to verizon and have them fix it, but I think I know how that conversation will go...