I'm not going into the legality of what has been discussed off-topic.
I will however say that since implementing OpenCL, we have had a number of users complain about performance. We offered two lots of advice—either disable OpenCL or try and diagnose the issue and ensure things like your graphics drivers were up to date. Disabling OpenCL will just leave you with exactly the same performance as before OpenCL was implemented.
Your Nvidia GTX 1060 supports OpenCL - if OpenCL is not working on your machine, there is a conflict somewhere in your system/drivers. We have machines with 1060's and other 10 series cards, as well as 20 series and 30 series all of which working with OpenCL.
The fact your Windows Explorer has issues after Affinity shuts down also suggests potential issues with the machine. You can say other software doesn't do this but not all software works the same way. Another point you made 'so slow, especially browsing for files' also suggests an issue rooted within Windows Explorer - we just call Windows Explorer. Do you have any apps that handle thumbnail previews?
Yes—if your system is healthy and configured correctly. Your graphics card, as mentioned above, supports OpenCL and should be working. You said you can't enable OpenCL which again, is odd - you should absolutely be able to enable and disable it at your leisure. The fact you cannot enable it suggests it might be a driver issue or something else...
What is your renderer set to currently? WARP, Intel or your GTX card?
What version of Widows are you using? Can you press the Windows key and type winver and paste a screenshot here. Also, can you provide a screenshot of your dxdiag screen for both system and display?
Finally, go to C:\Users\yourusername\AppData\Roaming\Affinity\Photo\1.0 and attach the Log.txt
I am sorry you are having issues but there are thousands of hardware and software combinations on Windows and it's not easy to diagnose and fix absolutely everything - but we can try.