Bear in mind, it is a large assumption to say that "When students ask for quotations on eNotes, it is normally to cheat on such assignments ...." Granted, there are students who have not got bright ethical light bulbs under their bonnets, and there are students who are manipulative, but these do not represent the "normal" student: never have, never will. The "normal" student has a thirst for learning of some level or other.
That said, many of the questions that you represent in your brief remarks are obviously questions written by a teacher and directed at the student; this is especially obvious with the long preambled ones and the ones with curt commands, like "Explain." or "Defend." or "Support with quotations." These curt commands--meant exclusively for the student and not for eNotes Editors--should be edited out and ignored. The question must be answered, but the commands to the student should be removed.
Long preambled questions go something like this: "Consider something something something then think of how it reflects society's something something something. Now answer why Elizabeth reacted the way she did to Darcy's letter after his rejected proposal. Explain with 5 quotes."
These actually should be edited to the simple question contained within the elaborate whole. You should reduce it so the final answered version is like this: "Why did Elizabeth react the way she did to Darcy's letter after his rejected proposal?"
Voila. 5 quote dilemma and doing the student's work for them dilemma eliminated. Now your answer falls into the category of tutoring or providing expert reference material akin to that in any encyclopedia or literary reference source, which can be cited (indeed, must be cited if used) as can any other legitimate reference work, for we are after all, experts, are we not?
One caveat. Editing the question must not change the intent and/or meaning of the question. For instance, the final form of the above example must be: "Why did Elizabeth react the way she did to Darcy's letter after his rejected proposal?" This is what the student asked. It may not be turned into something like: "How do I write an essay about Elizabeth's reaction to Darcy's letter?" This is not even remotely what the student asked.
Bear in mind, you are under no obligation whatsoever to provide quotations for students on eNotes. (1) You may entirely skip such questions. (2) You may answer without quotations at all. If you choose option (2), you will do so without expectation of a Bonus payment, but you may certainly so choose.
Another kind of question that poses an easily reduced ethical problem is this type: "What are a lot of quotes that show Mr. Darcy really has a good heart?" This you will edit to: "What is one quote that shows Mr. Darcy has a good heart?" Another is this similar type: "I need help finding a lot of quotes that show Darcy's character development." This you will edit to: "What is one quote that shows Darcy's character development?"
Again, voila. Quote and doing students' work dilemmas banished.