Root needed for maximum numbers of apps.
1. First of all, edit build.prop, find "ro.build.type=user" and change it to "ro.build.type=userdebug" (use es file explorer or any build.prop editor)
Flash already edited build.prop flashable zip in recovery. Download from here
3. Download calender, books2, drive, keep2 from here (other apps not tested but working links for them are below):
4. Uninstall old Exchange services (use any app like titanium backup) then install Email, exchange services, fit, from here
5. Play services (download from play store) or from here:
6. Search and launcher from here
7. Messenger from here
8. Play music from here (suggested to update from play store)
9. Uninstall old Gmail from system (use titanium backup or any other app), reboot, then install form here
10. Keyboard 4.0 (read notes on how to install):
lib OR Download this and flash in recovery.
11. Sounds (Flashable zip) from here
12. Fonts (Flashable zip) from here
13. Icons (Flashable zip) from here
14. Bootanimation and Logo (concept) from here (by me)
15. Install Xposed framework from here
16. Download and install Android L theme from here (Thanx Paras Jasal for fixing the theme and uploading and Yogesh Gosavi for re-uploading and providing this link)
17. Download HKThemeManager from Xposed itself and enable it. Reboot.
Apply Android L theme in HKThemeManager and reboot.