I found the sound lacking with just the dash speakers and door subs, the rear speakers do make a difference. I got the kit in the link I send above, here is what they look like fitted:
I got this camera, it really is tiny. The reverse lights are plenty bright enough to use at night whereas the colours are fab during the day. It switches to reverse view on the HU when you select reverse:
New Car Rear View Camera Reversing Camera Parking Line PDC Dustproof AW45 | eBay