Managing File Associations on Windows

How do you manage file associations on Microsoft Windows? I enter them directly in the registry using Registry Workshop, which allows to copy entire keys in an Explorer-like interface. Earlier I used Regedit. I've defined file types for every extension beginning with "ZZ_" to organize them together. I've added three generic editors (emeditor, winhex, notepad) to the asterisk "*" extension.

There is considerable redundancy in commands. Some file viewers are applicable to many types (IrfanView, media players). Other commands are specific to one or two formats. Merging all image or sound files into one file type is not convenient. This would also lose distinct icons for each format. Is there a tool that would allow one to define a command with its name, and then allow to quickly add it to specific file types via checkboxes or similar spreadsheet layout? The tool would be useful for setting up a new computer quickly.

Association function in application software is mostly rubbish. They register themselves as the only program with the ambiguous "Open" verb. It is not easy to tell which program would be executed. Sometimes an association is stolen, and it is still called "Open" afterwards. Only some tools offer to add themselves as secondary types.

I've tried "WAssociate", which is good, but not much more than Registry Workshop with a Browse function for commands and icons. I would probably use it for the registry tree copying functionality.

I have to guess what "Default Programs Editor" does because it requires the NET Framework. These days computers are so obscenely fast that entire games run in Framework, but I don't have it. Looking at the screenshots, it seems that it doesn't allow to share commands between file types.

What is the status of associations in Windows 10? When the system was new, word was that associations would only be managed by built-in OS tools. How exactly are they different there? Can you still set them via the registry, or have to do a dance with manifests or hidden accounts?