I was just thinking you might have meant that you were wondering if I was going to finish the DeviceCapabilities checking. Actually, I don't think I am. I'm currently checking that the printer has the paper bin that you're trying to set. Many of the other properties are checked via the BITAND function against the dmFields from the DEVMODE structure (i.e. duplex, orientation). For some, I'm not sure which constant to use for DeviceCapabilities, nor the length of the string for the buffer.
If there's a specific property you'd like to see me check, let me know.