So I have recently been having a batter at the tags to see if we can remove any we don't need. Define any that are undefined and re-tag those we think are redundant.
As suggested by Monica Cellio I will instead post an answer for each tag as well as what I think should be done with it, agreement / disagreement is then as simple as a up or down vote.
Feel free to disagree and explain why if you do so. I can't do the deletions myself so will rely on community agreement to determine what we should do with each of these tags.