Two orange/one white is a CPU failure.
Unfortunately, the cost to replace a board isn't trivial (the mainboard needs to be replaced). For an i3 system with Intel video, figure $300-350; it'll easily be $500-600+ for an i7 with discrete video.
There's no way to know. Could be a bad CPU (which is rare) or a bad system board (which is much less rare).
If you haven't tried a system reset (unplug the system, remove the base cover and disconnect the battery, then hold the power button for 30 seconds and try restarting), it's worth trying that before proceeding with an expensive repair.
The 1 white and 2 amber diagnostic code represents a CPU failure.
The system will not shutdown when displaying the Diagnostic Error Codes.
Diagnostic Error Codes will always supersede any other use of the LED. For instance, on Notebooks, battery codes for Low Battery or Battery Failure situations will not be displayed when Diagnostic Error Codes are being displayed.