If i use the MCP library from adafruit on arduino will it interface with the mcp chip via sca scl on the board without changing the pins or do I need to remap the pins
You will need to supply 12VDC to the relay controller. It is required since the relay coils are 12VDC and cannot be powered from 5VDC supplied over the USB connection.
Yes, the Adafruit library should work just fine, we connect the MCP23008 to the default SDA/SCL lines.
Currently we do not supply schematics for the boards, however the setup is pretty simple, relay 1 connects to MCP23008 IO 1, relay 2 to IO 2, etc.