Alternative Uses for Sideboards / Arduino Alternative

[Spb2005]

Hi,
I have a few sideboards lying around and was wondering if I could repurpose these boards for other projects, like a simple Neopixel controller or similar applications. Essentially, I’d like to use them as an Arduino alternative.
I have a few questions:

1. Is it possible to program and flash the MCU using the Arduino IDE?
2. What voltage range does the +15V pin support? (e.g., can the board be powered with 12V or 5V?)
3. How much current can the buck converter handle at 3.3V and 5V?
4. Is there a complete schematic of the board available?
5. Would it be possible to connect other I2C or SPI modules/sensors?
6. Is there a way to retrofit a WiFi module onto the board?

Thanks in advance for your help!