Quetions about Analog Infrared CO2 Sensor SEN0219

Hello, I just got a SEN0219 Analog Infrared CO2 Sensor and connected it to an Arduino (signal at A5). I am running a very simple sketch, simply printing out the pin value:

Serial.println(analogRead(A5));
delay(25);

A graphical sample of the output is below. Now, I have some questions:

1 - Cycles in output: you can see there are spikes in the output. These are periodic, start of spike to next start of spike period is roughly 2 seconds, with each spike lasting just under 1 second. The sensor has a white square on top and on that white square, 4 red LEDs light up during the duration of the spike. What does this mean and which is the right value? Should I average over 2 seconds? Should I try to identify the spike and average over its duration? What is the meaning of the red LEDs?

2 - Where is the sensor? I presume somewhere behind the white square? I am asking because it takes quite some time to respond when breathing next to it (see image), something of the order of 10 seconds and takes a tremendously long time to fall back to normal levels, even when moving it around and fanning it (something of the order of minutes).

I want to place it in an air stream. Which side should be facing the stream? What kind of response times should I reasonably expect? How sensitive is it to temperature and humidity changes? Is there a datasheet for the actual sensor I can have a look at?

Thanks.