[Nexus 4 Q&A, Help & Troubleshooting] Planterz:
You made a wise choice, young padawan.

Yeah, that looks to be the entire front assembly, including the screen+digitizer, already installed in the bezel. Also includes the earpiece plus the speaker grill that you're missing. You'll have to swap over the guts, and that's about it. It's easiest to swap the power and volume rocker buttons first since it's a bit harder to get them where they go if you've got the logic board in the way. Just remember that the contact points need to make a ^ rather than a v when you're assembling it with the screen facing down. Tweezers are good to have, especially if they're very long and even better if they're curved. I also recommend doing this over a clean towel to avoid scratching the screen (there'll probably be a film over it too), and the fluffier the towel the better, to catch the tiny screws from flying and disappearing.

Honestly, getting the 2 halves apart is probably the hardest part. They make specialized tools for this, and often the sellers will include them, but it doesn't look like your purchase includes them (mine didn't either). Something plastic is the best choice, since you're less likely to cause cosmetic damage to the plastic (especially the bezel) if you slip (and you will slip). As I said before, GO SLOWLY. Work it apart a little bit at a time, alternate side to side, starting from the bottom. Eventually you'll be able to pull the 2 halves apart.

The battery will be stuck in pretty good and will need to be pried out. If I were you (and a week or so ago, I was you), I'd pop a new battery in while you're at it. At this point in the phone's life, it's probably had at least a few hundred cycles on the battery and has lost 10-20% of its original capacity. The other components shouldn't be nearly as hard to get out. Just pry in various points until the piece pops out. Do not force anything. Just work it out slowly. After you pop off the piece that covers the USB port, there's the board that has the port, and that can be slightly tricky to get out. Best way I found is to slip something small and flat (screwdriver?) into the port and push up and out, and the board should come out easily.

Thankfully, there's only 3 different screws used, and they're all easily differentiated from each other. There's the 2 T5 TORX that hold the halves together, the 2 very short screws with wide heads that hold the battery in place, and the rest that hold everything else are all identical to each other.

It looks like on your assembly, it comes with its own adhesives. Everywhere there's a blue film, pull it off and there'll be adhesive underneath. I'd recommend leaving the film on over the part where the sensor/headphone jack module goes until you're sure you can stick it in place with the proximity sensor not acting wonky. Download an app (I used Phone Tester) that can read the prox sensor. FYI, as long as everything is in place, and you've attached the battery, you can boot the phone without replacing the back cover, and test the sensor (just depress the center bit of the power button board). You don't need to screw everything in, but you should at least screw and tighten down the few that surround the sensor area. Once you've got it reading properly (best of luck), it's time to put all back together.

You should familiarize yourself with the teardown/reassembly guides out there. Go to ifixit.com and have everything ready to look at. This is the video that I used to guide me, and I watched it through a few times before I attempted it myself. You should be just fine with your phone after familiarizing yourself, but if you have any specific problems or questions, feel free to ask, and I'm all too happy to help.