Suggest goes to TWRP 

Nexus 5 How to unlock

Edit: Fixed 

You can try Philz CWM Recovery as well, been using it since my HTC days

http://forum.xda-developers.com/google-nex...esture-t2565174

How you root in the first place? You root via fastboot?
Installing recovery is not difficult once read and understand the process.

No problem, glad could help 

GravityBox is pretty good enough as it has a lot of features to tweak the looks. Can use to change the nav bar.
Sorry, but I can't recommend you any Xposed module because my needs are not the same as yours. But I can list down those that I use:
-Greenify
-Network speed indicator
-XPrivacy

Can go have a look in the Xposed section @ xda, maybe you can find what you're looking for.

settings

go to about phone n tap 7x of build number

den u'll see the magik of the developers opt.

n tap-n-scroll it till the runtime , once u saw it n switch it as well

Ta-da

another magic is done

[Explained] ART Runtime in Android 4.4(kitkat)
To enable ART, go to Settings > About phone. Tap on the build number 7 times then go back to Settings and you'll see Developers options about About phone. Go into Developers option and change runtime to ART.