gpedit.msc

Group policy is edited on a local per-machine level using the Group Policy Editor, or gpedit.msc (stick it in your Run box).

Computer Configuration \ Windows Settings \ Security Settings \ Software Restriction Policies \ Additional Rules

Right click and add a new path rule. Then disallow Edge's path. On the machine I'm sitting at it's c:\Program Files (x86)\Microsoft\Edge\Application.

Just disallow everything in there (*) and any time something tries to launch Edge in your face you'll get this:

Look at me. I am the administrator now.

If you are on a non-Pro version of Windows and don't have access to the Group Policy Editor, you can just use this which is considerably less hassle.

Not that I've seen, at least not in the IoT versions of 10 and 11 we're currently running. Although there are some hard-coded functions wherein Windows will disrespect your default browser assignment no matter what, such as pressing F1 for help in Explorer. Since we have Edge disabled entirely on all machines here, instead when you do that nothing happens.

If you are a cog in the corporate machine then yes, probably. Ask your IT people. But in my case in particular (and probably lots of others) I'm saddled with Windows at work because some of the software we need to use doesn't work in Linux. And no, it doesn't work in Wine either before the inevitable comment appears. I try about once a year to see if the new versions have gotten compatible enough. The answer is consistently no.