I've had a Nexus 5 since they launched and have done a bit of tinkering. You should do some research into "custom ROMs", these are basically custom versions of Android that are made by people taking Google's source code and editing it to make a new version which they feel is improved. If you do some research into this and decide that it might be for you then you're in luck as Google devices have the best developer support, after messing around quite a bit I highly recommend flashing stock 4.4.2 for the latest bootloader and modem, then unlocking the bootloader, installing TWRP, then installing OmniROM (with PA GAPPS) and use franco.Kernel as your kernel, I find this to be a really clean combination with the best speed and battery life, OmniROM gets an update every day on the nightlies and the guy who develops franco.Kernel is currently being hired by Google I think. In terms of cases I don't use one myself however apparently the CruzerLite ones offer very good protection (as shown at
), the Spigen Neo Hybrid is also a very popular case.