Actually, your choices here are quite varied. And scotty85 is correct that all you need to do is load the APK file directly and not update it (make sure you turn off automatic updating in the Play Store), the one you need is Google Maps 6.14.4 and it is available all over the Internet, try here first:
Google Maps 6.14.4 Apk 1702 - Home APK
As far as ROMs go, there are LOTS available for the Rezound, the kicker is each phone is a little different on how it reacts to various JellyBean/KitKat ROMs, some work better than others on various handsets.
Some good places to start would be:
EclipticRez (ICS)
Beanstalk (JB)
Evervolv (KitKat)
VanirROM (KitKat)
Tachyon (JB)
LiquidSmooth v2.37 (JB)
CarbonROM (any JB version)
All can be found at XDA in the Rezound Development or Original Development forums... Of those, EclipticRez is probably the most stable overall (it is a semi-stock based ICS with Sense 4.1 over top), followed closely by Tachyon and LiquidSmooth/CarbonROM, and for the most stable KitKat I would go Evervolv then Vanir.
Note that most KK roms have camcorder issues, some work on some handsets and not others. Unfortunately, most of the hard core developers are moving on to other phones, so development on this device has slowed greatly in recent months.