To really get in there and get your hands dirty tinkering with a tablet, you need a good custom recovery. The Samsung Galaxy Tab Pro 12.2 is due for some tinkering today as TWRP comes to Samsung's biggest Android slate. You can grab the files right now on the TWRP device page and get flashing.
TWRP is, of course, one of the most popular custom recoveries for Android devices of all shapes and sizes. You can use it to flash any old ZIP file you want to a device. That includes complete ROMs, assuming they've been built for your device. TWRP tends to get updated frequently and it's completely touch-enabled.
Samsung devices are a little different with regard to installing TWRP than other hardware. You can do the regular ZIP flashing method, the ADB image, or Odin. Grab the correct file from the link below and use caution. Also keep in mind this is the WiFi version of the tablet only—not that fancy LTE one.