Is there a way to list all the tags?
I want to know all the tags that I had put in. Sometimes I might give similar but different tags to the same kind of task e.g. @job, @cv, @career etc. for the same type of taks.
Do we have a functionality where I can list all the tags put by me and then edit them so that they are automatically reflected in my tasks/projects?
yes, it is possible to list all your labels by using the @ query. This will allow you to edit your label's names or colors and all changes will be reflected on your task lists. However, this - among many other great features - is only available with Todoist Premium.