First off, if Apple doesn't actually look at the forums, then I don't know what to say--no matter how I typed in my problem when wanting to report an issue and get help on it from Apple support, they kept saying "please type in a valid issue", so that's why I posted about this here. They have no way of letting people report a general issue, it has to be on the list of things that they think are "valid" issues.
And yes, Apple is probably going to be given a problem over this, probably lawsuits, as I know I'm not going to be the only person having this issue. Computers overheating and CPUs frying because of bad software is not going to be taken lightly by some people. So don't act like I'm over-reacting to this. Apple has had over 6 months to create a new version of iTunes that's fully compatible with Windows 10.
As to your questions: I was running Windows 10 Insider Preview since sometime in February, and I upgraded to the full version on the 29th of July. So yes, my system runs Windows 10 just fine. What made me even look at the task manager in the first place on my July 29 install of Windows 10 was that when I was editing videos, the CPU fan was on full speed and I kept hearing that little "beep" sound that shows that the CPU is getting a little too hot.
Fresh copy means within an hour of installing Windows. By the time I had typed the OP, it had been 8 hours, as I was researching this stuff to make sure I wasn't jumping the gun.
At somewhere around the 1/3 mark of installing iTunes, the CPU went to 99% and never came back down. After I had thought the reason why I was having the same problem in the previous install was because of PhoneTrans (to transfer files back and forth between my computer and my iPhone so I could easily make custom ringtones), which it wasn't, but I wasn't going to take any chances and never installed that again. So after I had reinstalled Windows 10, I ran the Task Manager and watched the CPU usage for every program I installed on my computer. I installed 3 other programs, one of them Chrome, and when iTunes came up, about 1/3 of the way through, the CPU went to 99%.
After it fully installed, I then tried stopping all Apple services in services.msc. Didn't help. Then I stopped all Apple processes. Didn't help. Then I uninstalled iTunes. Didn't help. Then I restarted after all that. Didn't help. The CPU was still at 99%.
Then I reinstalled Windows yet again and reinstalled ALL my software which is where I'm at now---no problems at all, and I'll most likely continue to not have problems as long as I don't install iTunes or do something foolish.
Granted, I've already been rather ***** that I have to go through so much major hassle just to transfer files between my computer and my iPhone (I've had this iPhone for about a week now) because of how Apple has everything locked down--I'm used to Android phones where that sort of thing is really easy, but I was tired of voice-to-text not working correctly on Android as well as so many horrible slowdowns (and even on my new iPhone, I'm finding that unless I'm in a good wi-fi range, it lets me transcribe about 4 or 5 words and then it stops and I have to hit the space bar and start voice recognition again, I've been very disappointed in that, it means that some of my whole reason for getting an iPhone has been in vain). I've found that the best way, so far anyway, to transfer files is to send myself an email with an attachment. If Apple doesn't release a compatible version of iTunes, I may end up having to jailbreak my phone, which would be a shame to have to do.