I'm waiting for a full report on that UHD screen! I'm gonna wait for a good 4k computer monitor. My unlikely-to-be-fulfilled dream is that NEC will soon produce such a monitor that works with its Spectraview automatic screen calibration software. In the meantime, I think I'll try to schmooze Best Buy into letting me plug a USB thumb drive into one of their 4k TV's.
Don't worry about grading! It's easy, especially if you've ever used PS or LR or ACR or whatever. The paradigms used by video are a little different however. Watch a couple videos on the Reference Monitor, which is the video equivalent of a histogram. Start out with Fast Color Corrector, it's usually all you need. But there are some really jazzy tools that you may start wishing were available in PS as well! But bottom line: less grading is better than too much grading. The best goal of grading is to make a sequence of clips seem related in color, contrast, lighting, and maybe even time of day and weather conditions so that they flow into each other without visual bumps. You've got to find a common "look" denominator among your clip sequences, and then figure out what kind of look you impose on the group of them that will work within the limitations of the technically weakest clip.
FWIW, I've noticed a trend among newbie GH4 users to fiddle with the "parameters" to get either a more "cinematic look" or a file that is somehow "more gradeable." I think this is a mistake that creates data-poor files. Yes the files wind up looking like genuine, simulated low contrast raw files, but unfortunately they are really just data-starved mp4 files that only get worse with the slightest grading! Such files more closely resemble dim projection at the 48-plex, rather than anything I would call cinematic. I have not done exhaustive tests, but my one test with online-recommended, so-called cinematic parameters was conspicuously disappointing compared to leaving all the parameters at "0" which yielded a much richer and more malleable file that could easily be graded down to "cinematic" in PP, if I foolishly chose to do so.