Project status:
Sound: Working! (VoodooHDA 2.8.4).
Network: Working!
WiFi: Working! (BearExtender...)
Battery meter: Working! (more or less, VoodooBattery *sigh*)
Pretty much everything is working now. I used your kernel patches, and I removed the NVDA* and GeForce* kexts. Then I repaired permissions using Kext Utility (I hadn't done that before) and now the unique fail is the graphic bug in the login, which now is much, much smaller. So now it is pretty useable.
Thank you for everything!
P.D.: Don't hate me too much...
P.D.2.: I'll keep looking for the solution to this glitches. I've tried using different boot flags (IGPEnabler, IGPlatformID, IGPDeviceID...) without success... EDIT: Can the eDP screen be problematic?