Server resources and publication

I am wondering what the effect of making publications non-reactive by using this.added() has on server resources?

We have a large number of documents in our collections so when we subscribe we pass criteria down to the server in the getMeteorData functions to limit the number of documents sent to mini-mono.

 Meteor.subscribe('pubText', some_criteria);

This causes every client to pass different criteria down creating a huge number of reactive publications.

First question. When do these publications on the server get cleared up?

Second question. If the criteria differs in the query does Meteor cache the result separately?

Third question. If instead of returning a cursor I switch to adding docs to the collection to remove the reactive feature of publications, do I save a significant amount of resources on the server?

    results.forEach(doc => this.added('collection', doc._id, doc));