A few things here,
First off, the 24/32 bit issue is not actually a problem, the extra 8 bits in Windows is the Alpha channel, which Linux automatically uses if available in 24 bit mode. Stick with 24 bit, it's the same as 32 in Linux terms.
The problem with lower frame rates is an issue in Wine/Cedega. As with all emulators and compatibility layers there are speed issues. Especially in DirectX layers that use OpenGL as a renderer, if LFS was OpenGL then it would be much quicker (OpenGL is the 3d renderer used in ALL Linux distros). This is coupled with the fact that in my experience, nvidia's drivers in Linux are slower than they are in Windows. Both of these add up to make a significant overhead on the graphics card.
The 75% CPU issue is one with LFS. It refreshes the physics at 100Hz, no matter what the frame rate on the display. If the CPU is not fully stressed at 100Hz physics updates then that will cause the CPU to be less than 100% utilised.
The illumination issue is one in Cedega also. This is caused by an over-expansion of the shadows, and can easily be solved by turning them off. It is an annoyance though.
The sound issue is unknown to me, I've never actually had that issue myself. All I can suggest is disabling music, IMO it's not needed (and quite frankly crap) and takes away from racing.
Hope this helps a bit, it's about my limit as far as Linux + LFS goes, but I'm sure others know more