Those features are specific to the nexus 5. You can get the Google now launcher by looking in the themes and app section of the htc forum. The icons are also specific to the nexus 5. Not sure 100% but n4 also got those icons. Album art and certain tiny things were also exclusive to nexus 5 or stock Roms. Have you tried any gpe 4.4.2 Roms? I was on the htc one but moved on to the nexus 5.

Sent from my Nexus 5 using xda app-developers app