Check which version of WM comes on your phone...most likely, it will be 6.1. Upgrade to Verizon's WM 6.5 here (you get the upgraded radio) - no need to unlock the phone as this is the VZW shipped version
http://www.pcdphones.com/phone_downl...erizonWireless
Play with that for a while, then read up on which custom ROM you may want (and knowing the steps to unlock and flash a rom.
http://www.youtube.com/watch?v=syxN-w7qFtM (part 1)
http://www.youtube.com/watch?v=p0-7H3U9fzY (part 2)