Never pay an editor to revise or publish your writing. Some magazines, and book publishers are fronts for book doctors. They welcome your submission but then suggest a specific book doctor to get your work into shape. This is flim flam skim. I write short stories and articles.
Agents prefer to work with book authors or well known writers.
They are paid a percentage of your sale for selling your work. However, if you find an agent to represent your book, he or she may require you sell all your work through the agency. You might want to retain the right to market your articles or magazine stories yourself. They have assigned them the rights to market all their writing. They are restricted by the agreement with the agent.