Wireless charger in iMac usb port (Electronics guru needed)

My understanding of your reply is that it's okey to run the wireless charger off the iMac's USB port but it's not the best solution meaning it will take longer to charge but will not damage either the iMac or the wireless charger. Also that there will still be minimal current draw while the charger is plugged in yet not charging anything. My guess is that would be even less than having an SSD drive plugged in all the time.

Yes. Totally correct.

Why do you say it's "less than ideal" to use the USB-C/Thunderbolt 3 over the standard USB port? I thought it provided more power than the standard USB.

Less than ideal only because of the limited power (relatively speaking) of the USB-C / Thunderbolt ports on your particular model iMac. Only USB 3.1 "Gen 2" ports supply power comparable to the demands of that charging device. Newer Macs have them.

Apple designs protection into their devices, and external ports in particular. If there is the slightest possibility that someone will stick something in them, they will. It is certainly possible to inflict electrical damage but you have to work at it.

In my opinion you should not be running the wireless charger on ANY computer port. You should use a standalone power supply that outputs enough power to properly charge the device laying on it. The device you are using comes with a power supply block and you should use it. 10 watts is more power than any computer port can put out.

Question 1) Does it cause undo stress on the iMac port to leave the charger plugged in all the time (not necessarily charging all the time)?

No, but that iMac's USB ports will not be able to supply as much current as that device is capable of drawing or providing.

This makes me wonder if the charger is running current through full bore any time the charger is plugged in the USB port with or without even charging anything.

No but you would need to consult that device's specifications to be certain.

A definitive answer depends on the device's construction. If an inductor has no opposition to the magnetic flux it creates then it's not doing any work. No work = no power consumption and the only losses are resistive. The charging device will consume power for purposes other than charging but how much is unknown.

In other words it's certainly less than 100% efficient but it's probably close enough for the purposes you describe.

Question 2) If the above is okey, would it be beneficial to get an adapter and run the wireless charger off the USB-C port? I am not worried at all about fast charging, just convenience and not damaging anything.

You can do that if it's convenient for you. It's less than ideal.

Refer to your iMac's USB specifications.