Identifying piece of circuitry on a PCB
I've identified the resistors, but would be curious to know why they're all different,


If the lights are LEDs, different coloured LEDs can have different voltage drops so need different resistors to provide similar currents (and/or similar brightness)


  I also identified the transistors


TO-92 is just the case style. The devices will have an identifying number printed on the flat face. The photo lacks enough detail to see. I'd guess they provide current to the lights, perhaps the controlling IC (on the riser) can't provide sufficient current by itself. So yes, they're being used as switches.


  Ceramic Capacitors 


Because of their position, they may be part of the power supply?


  Tiny thing between the ceramic capacitors


A diode. The ZD marking suggests a Zener Diode used for voltage regulation.


  The upright board


Looks like a chip-on-board. There's a tiny silicon IC under the blob.

If you posted a photo of the tracks on the underside of the main board, it might help show how the devices are interconnected.