Yes, there are tricks to make their lives easier my friend. First of all, you can certainly send over a copy of your essays. That will give them some idea of what to say. Secondly, if they are veeeery busy, WORST case you can meet with them and ASK the questions, in person! Write down their answers, and at least you are in better shape than if you had to write the things yourself. At least that way, you get some fresh ideas, and some ideas that you may not have thought of. Hope this helps, and good luck!
Some supervisors might want letters- others might prefer point form reminders of what examples they may be able to use to answer each question. Don't coach them on how to evaluate you, just give them ideas on what might be good material to draw from for each answer.
Meeting to ask is another option, but then you run into problems of you are the one writing it- not them. Maybe better is to do the point form, and follow up with a meeting to explain why you think they're suitable examples.
There is no 'right' answer here. On the other hand, if the guy is really a good (and suitable) recommender, I'm sure they're willing to spend just half an hour helping you decide your future. Remind them how important this is to you!