I should have never bought this iMac, i heard they have problems but this is ridiculous. No one has an answer for this...
Typically, I have found it to be the other way around.. More issues and problems with PCs than with Macs once you have understood the differences and how to set them up correctly....
I should also add that I have several iMacs along with a bunch of other Macs, as do my clients.. and there are no inherrant issues with them at all... in regards to the kind of issues you are describing.
In almost every case where there has been an issue, in regards to external hardware, it has always been tracked down to drivers/hardware problems because Devs have failed to program/design the drivers or hardware correctly or it has been a 'User Error' that once corrected resolves the issue
I suspect you are simply suffering from the "I've bought a Mac and now things aren't the same as on my PC" syndrome... which is very common during the initial stages of getting accustomed to a new computer and OS...
Don't worry... you will get there eventually 🙂 and then, like most people, you will never look back!
Finally, and I am simply saying this because some peole simply don't like change and/or don't end up feeling comfortable with the differences between OS X and Windows...Don't forget that if you find you prefer the Windows way of doing things, you can always Boot Camp your Mac and go back to Windows.... so you will always end up in a win win situation.