It will not operate without a CPU.
iMac
It uses an Intel Quad Core i5 or i7 processor. This is an excellent CPU also used on Windows PCs.
The iMac is a fantastic computer.
The original iMac was actually 'Bondi blue' in color (Blueberry came later, and was slightly different). It featured a 233MHz PowerPC G3 processor.
No, the PC version will not work on an iMac. You need to get the Mac version.
Click the link.
Yes
Yes, it will work on Mac.
Mine works fine.
Yes, it works fine.
If you have the Mac version it will work on an iMac but the Windows version will not run on a Mac. It costs $6.99 on the Mac App Store. Click the link to get it.
The fan will work - but it will spin constantly - as it would have no data to rely on to regulate the temperature of the CPU.