Should we have a separate tag for each plugin, instead of a generic plugin tag to cover them all?
If so, what should be the naming convention for such tags?
Yes, create a tag for the plugin if you're asking a question about it. 200_success' suggestion to prefix them with
plugin- is a good idea.
plugin should be for questions about Vim's plugin system, in general. For eample: "In which directories does Vim search for plugins?".