COM Ports Questions

Hello,

This COM Port "stuff" is driving me batty.
Would be most appreciative for any help, as I really don't understand all its nuances.

a. In Device Manage, under Ports (COM & LPT), only one device shows.
A recently installed USB to Serial Converter for allowing my PC to control a shortwave radio.
Nothing else there, even if I click on the Show Hidden Devices.

I obviously have many other USB devices, such as my Printer, mouse, keyboard, and most likely several programs that have "grabbed" or use a COM Port for their usage.

How can I see a listing of ALL the COM Ports, if free, and who/what had staked a claim on
particular ones ?

b. what happens if several programs have been set up to use the same COM Port number, even if only one of them is ever active at a given time ? Is this allowed, or a no-no ?

Or, is it that irrespective of whether a program is being used or not, it must have its own, individual COM Port number ?
So, is it that no two anythings, whether being used or not, can be assigned the same number; true ?

If so, is all of this handled "automatically" by Windows ? Or,...?

Much thanks, and appreciate your help very much with my dumb questions,
Thanks,
Bob