Sadly, when applying for Social Security Disability benefits learning what your rights are is something you learn after the fact. Even then, chances are, you may never know what you missed out on. Disability Secrets is one of the most complete web sites and will walk you through the process and explain what your rights are and how to obtain them.
It is information that the Social Security Administration should make easily accessible through their own web site or through their representatives. Considering that 70% of applicants are denied when they first apply suggests that they have set the bar high and are not going to go out of their way to help you easily obtain the benefits for which you are entitled.
Social Security Online Electronic Booklet site has all of the best information that the Social Security Administration has to offer. It is their official site and the publications are authoritative.
Between the two sites mentioned you should be able to find answers to most of your questions.