1. You can keep everything stock and just get the bluetooth module from a camaro, it's directly swapable and gives you bluetooth streaming. Here's a guide for that http://www.cruzetalk.com/forum/137-...bluetooth-a2dp-bluetooth-audio-streaming.html
2. It's very very pricey in this car to get a stereo with all the appropriate harnesses and such, and unless you add subs to the mix, the speakers are not going to have as much "umph" as they (barely) do now.
3. You'll need to go aftermarket for these, as just LED bulbs are not bright enough for low beam use, and also don't throw light well enough in the factory housings. These are a "fan favorite" for aftermarket headlamps. They provide the best light output, provided you also get an HID kit with them, short of doing a full on projector retrofit. Winjet® WJ10-0324-04 - Chevy Cruze 2011-2015 Black U-Bar Halo Projector LED Headlights
Good luck cruzing