To answer your questions.... YES you should root your phone. No you aren't at any more risk than an unrooted phone*. You don't need to put a custom ROM on it, you can run stock and still see tons of benefits. That's what I do currently on my GN, and its what I would definitely do if the Razr was mine and not my wife's. The Razr has so much crapware that I cannot imagine running it stock.
My suggestion, root it, run it stock. Do some research in the ROOT forum regarding what apps you can freeze/remove and go from there. Once you are comfortable with the idea of "being rooted" you may want to look into some of the custom ROMs, but you can always go back to stock if you like. I'd also run a custom launcher/home screen as I hate the Razr home screen, but that's personal preference.
* Rooted or not, you can opt to install apps that don't come through the market - of course there are some apps in the market that are "bad" too. These apps carry some risk, rooted or not. Even if you did install a "bad app" you have to give each app explicit permission to access root. So if you install some obscure Chinese wallpaper app and it asks for root access, and you grant it, well then yes you could be in trouble.