I'm from the lupus forum, but saw your question and thought I'd pop in to help you out a bit. I have been on disability for 8 yrs now. When I filled mine out I had the same problem with space to answer some of the questions. Just put what you can in the space provided, put a small note "see remarks" and then in the remarks section put the question number and add the rest of your answer.
I hope this helps some and I wish you the best with your application and getting disability. Take care.