Or, can the Serial Monitor be used to monitor any Comm
Yes, it can open any serial port.
If so, how?
Select the port in Tools > Serial Ports, then open the serial monitor.
while( !Serial ) ;
just wait for a Comm Port to be created in the PC,
or does it also wait for some program in
the PC to Open the port?
It waits for a program to actually open the port.
Perhaps by re-selecting a Comm Port after the program
download is finished, and before opening the Serial
One simple approach is to program this sketch using the programming port. After it's fully uploaded, physically unplug the USB cable from the programming port. Look at the Tools > Serial ports menu while it's unplugged. Then plug the cable into the native port. When you look at the Tools > Serial Ports list again, the newly appearing port is the one for the native port, so choose it.
Then open the serial monitor. You should see the test run in the serial monitor window for 15 seconds. If that works, close the window and open it again. Each time you reopen the serial monitor window, the test will run again. Get that working before you try running serial_read.exe.