Google Nexus 4 — update.

to get the update ota, as in directly from Google, you must be completely stock with no modifications i.e. no root. You'll have to either unroot to do it, or sideload it (flash through a custom recovery). Check on xda forum, it's pretty straightforward.

It should be, here's an XDA thread on how to do it.

Apparently the update server is down at the moment, but check settings/about phone/updates. There is a 4.4 PA rom, available from the official website here. The Nexus 4's codename is Mako, if you didn't know. If you're unsure on what to do you can ask here or on xda.

I know it can be a little intimidating if you're not sure what you're doing or why you're doing it, but the beauty of Nexus devices is the ease of modding them. While no phone is unbrickable, nexus phones are almost always recoverable and have huge support on XDA and other forums.
The basics are this (for nexus phones only):
To flash a custom rom then you must have both a custom recovery (either cwm or twrp, or based on one of them. I use twrp and the instructions are based on this) and an unlocked bootloader. In your case, as you already have a PA rom on your N4 then you must already have these, but both can be done by either flashing the relevant zips from your phone or using fastboot/adb (from your pc/laptop/mac. )
Most non-stock based roms (i.e. CyanogenMod, PA, AOKP, Miui, etc) require a separate zip for google apps. This can be found on either the rom homepage (if you want PA then visit getparanoid for both Gapps and the rom for the Mako) or other sites like XDA, goo.im and so on.
The rom thread will advise if a data wipe is required. You may need this coming from 4.3 to 4.4, but check the XDA thread. Always make a nandroid backup before flashing or wiping anything, just in case you have a bad download, or are unhappy with the newer rom, plus you can restore data from your backup (sms, call log, apps, etc) using an app like nandroid manager. To save space you can move the backups to your pc.
Download the zips (rom and Gapps), and transfer them to your phone memory card.
Enter recovery (On the N4, power off your phone then Press and hold Volume Up, Volume Down and Power buttons simultaneously)
If you want or need to wipe your data select wipe and factory reset(it wont touch the sdcard), also wipe the cache.
After that go back to the recovery main screen and select install, navigate to the folder where your zips are, select them (rom first then Gapps) and flash them.
Reboot. The first boot may take a few minutes.
And that should be it. The same goes for flashing kernels or mods and is pretty foolproof (a long as you flash the correct zips for your phone/firmware, as a custom recovery can only check that the zip is in the correct format, not if it's for your phone or not). Basically it's download the roms/mods you want to your phone sd card, and flash them. If there's anything you want to clarify feel free to ask. If you want stock 4.4.2 on your N4 without going through unrooting/relocking your bootloader then it's the same procedure, without flashing Gapps as they will be included in a stock rom.