There is a sample pipe that index txt documents and it is in the sample project in this post and you can use it as a base pipe for pipes that will index specific documents or extend it. Right now it is not on our Roadmap for the next release.
And the answers for the questions :
The fluent API calls the publishing system automatically. Nevertheless we have a problem now when you try to publish or delete an item with specific facades. If you are using
App.WorkWith().AnyContentItem<T> it will work fine and will call the publishing system (this includes the search also since it is built upon the publishing system) for any action like Delete,Create,Unpublish or Publish.All the best,