DrDevinRX

The performance difference is negligible for the cards. If you don't mind shelling out a little bit more for the 12GB, I would just get that one. Performance difference: https://www.techspot.com/review/2390-nvidia-geforce-rtx-2060-12gb/

750W should be enough for a 4070 Ti. The RM750 (non e) should be fine for the GPU. I don't personally like the e variants of the RM series. They're just using cheaper components to slash the price. 850W would probably let you keep using that PSU for your next build, so you could pick up an RM850 or a Seasonic Focus 850.

The R5 1600 has more threads than the i5. This can be used for content creation or streaming which requires more threads to operate smoothly. For example, you can more easily stream on a 1600 than on the 8400 without dropping frames both in-game and on stream. This may even allow you to stream at a lower x264 preset or with higher bitrate creating a better looking stream.

This build should be fine for what you want to accomplish.

That motherboard probably takes a proprietary power supply. The only way to remedy this is to find what wires on the original PSU correspond to what and rewire your existing power supply with the correct connectors.

Are you running your RAM on its XMP profile?

Everyone loves the "move the window around the desktop" game. Otherwise, I would do as @G27Racer_188 said and test going between 60Hz and 144Hz.

It will give you the option to keep your files or completely erase the drive. All of your programs will be erased regardless.

Unfortunately, Microsoft reduced the rollback time to 7 days from update time. The only way to go back to 1709 at this point is to find a 1709 ISO and reinstall Windows.

If you have 4TB of storage, what did you fill your SSD with? In any case, get another SSD, 16GB of RAM is fine.

As long as your controller supports hot-swap, it should be fine in Unraid. If you go this route, I highly recommend installing the Unassigned Devices plugin so that you don't need to add the drives to the drive pool and format them and can just create a share with them.

For the NAS portion, you don't need to install a third OS. You can just use Unraid itself as a NAS and create shares and map them to the other VMs. Plus in Unraid, you have dockers for other things.

You don't need a GPU for every VM you deploy, but it is recommended that you use a cheap GPU for Unraid's console output. If you don't mind working through a VNC connection, SSH, or using the built-in VNC client, you don't need to get a GPU for your Linux VM, but it may implore you to get a low-powered GPU as there is somewhat significant input lag using the built-in VNC client. You can easily switch the GPUs that you passthrough to the VMs through the web interface.

POWER_SW = POWER_BTN I'm fairly sure.

You should be able to clone your drive without any issue. Afterwards, you will need to expand your partition or create a new one to fill in the empty, unpartitioned space in Disk Management (diskmgmt.msc).