Backlight issue is because you have no SSDTs installed. From bootlog:
Code:
Read HFS+ file: [hd(0,2)/Extra/DSDT.aml] 78270 bytes.
[B]ACPI Table not found: SSDT.aml[/B]
FADT: ACPI Restart Fix applied!
FADT: Using custom DSDT!
Found ACPI CPU: CPU0
Found ACPI CPU: CPU1
Found ACPI CPU: CPU2
Found ACPI CPU: CPU3
Found ACPI CPU: CPU4
Found ACPI CPU: CPU5
Found ACPI CPU: CPU6
Found ACPI CPU: CPU7
SSDT with CPU C-States generated successfully
P-States: min 0x8, max 0x16
SSDT with CPU P-States generated successfully
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
RSDT: Added 2 SSDT table(s)
FADT: ACPI Restart Fix applied!
FADT: Using custom DSDT!
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
OEM SSDT tables was dropped
Added 2 SSDT table(s) into XSDT
Audio problem is because DTGP is referred as External in DSDT but then defined nowhere.
Also, in this ioreg, power management is all wrong. You're using Generate[PC]States=Yes and have no custom SSDT.