IMHO it seems that the recent edit of key info by Tim should do the job of steering people away from using this tag. At last check there were only about 60 questions using it. Editing to remove/replace it on those questions using it would seem logical to me due to it's complete lack of precision. Those who follow key may have a different view. I don't.
I would say no here.
The prompt is a specific (and independent) aspect of a terminal system. While prompt-related questions can live under command-line, so could bash.
They seem distinct enough to be different, so they seem okay to stay. However, prompt should be edited to reflect this difference and make it clear what this question is to be used for (...
Yeah, I think we can safely roll packages into package-management.
There are probably a few exceptions but I don't think there are many questions where package-management wouldn't apply. [To the wider meta audience] let me know if that sounds desirable or not and we'll make it happen.