Hey @benchang , great meeting you last week, hope you're having fun working on the board. We interacted through email, but I'm posting the same info here, too. Posting some basic info, but hopefully there are others who can help, too.
If you need real tech support, here's the office support page: https://www.renesas.com/en-us/support/contact.html
For the light sensor, I believe you're looking for the Proximity Sensor, TMD3782. See this: http://learn.iotcommunity.io/t/ams-environmental-sensor-light-air-quality-temperature-humidity/39
Proximity Sensing with the TMD3782
The TMD3782x device will perform color temperature measurement, ambient light sensing (ALS) and proximity detection with background light rejection. The device detects light intensity under a variety of lighting conditions and through a variety of attenuation materials, including dark glass. The proximity detection feature allows a large dynamic range of operation for accurate distance detection, such as in a cell phone when the user positions the phone close to their ear. IR LED sink current is factory trimmed to provide consistent proximity response without requiring customer calibrations. An internal state machine provides the ability to put the device into a low power state between proximity and RGBC measurements providing very low average power consumption. The color sensing feature is useful in applications such as backlight control, solid state lighting, reflected LED color sampler, or fluorescent light color temperature detection. The integrated IR blocking filter makes this device an excellent ambient light sensor, color temperature monitor, and general purpose color sensor.