A quick peek at both TC:E and CQB sounds and they are all .wav files so I'm not convinced about the bit rate argument yet.
OK, there are some that aren't top notch quality but that's far from the clipping that was going on in the first alpha release.
As for the coronas, they are map entities which simulate the glow around the light sources.
Some console commands to check out:
cg_coronafardist 1536 either the size or cull distance of corona effect
cg_coronas 1 toggles the corona effect around lights
In-game each one adds an additional plane (two polygons) around the light source so it's natural that some players will want more control over them for optimization purposes.
I like the idea of new weapon sounds.
Dynamic eye mimics eye's adaptation to brighter or darker settings than the one you're currently in.
For an example, when you're in a dark room looking at a sunlit exterior it might seem brighter than it actually is. Then, when you get outside the brightness normalizes but the interior looks darker.