Most of questions might only need the series tag. E.g., if you already have a tag for akira adding plot-explanation seems redundant, because chances are you are asking about something plot-related (e.g. In the manga, why were Tetsuo and Kaneda fighting during the Y incident?). However, there might be some requires that require more context. E.g., if you want to know something specific about the author of Akira, tagging akira and manga-ka might make more sense.
If you are asking about what certain "sound effects" mean, it might be more appropriate for JLU. But if you are asking about a specific interjection a particular series's character, like Kinomoto Sakura's "hoe" exclamation. It can easily just fall under the card-captor-sakura series tag with maybe a character.
Tags like production and culture might be useful when asking general questions about anime/manga production (How did Type-Moon go about making Tsukihime?) and otaku subculture (Why are French maids the most popular type of maids in anime and manga?).
How do we make sure the tags are properly utilized?
Should we make guidelines for tagging non-series meta tags that don't correspond with any specific content, so we can avoid unnecessary/excess tags?