The downside with Medicaid is that they will make you divest any property you have to pay them back. In Karens situation it works well for her boyfriend since he is not on the deed. You are automatically qualified for food stamps if you're getting SSI by the way.
I looked at the SSI elibility and you can't have more than $2,000.00 worth of liquidable assets, They don't count one car or tools of the trade.
SSDI is the Social Security version of version of long term disablity insurance - you must have paid into it for quite a while to become eligible. I found an interesting link on detailed definitions of how they make the determination for cancer patients.
http://www.ssa.gov/disability/professionals/bluebook/13.00-NeoplasticDiseases-Malignant-Adult.htm This is a link to the benefits screening tool which will determine what program you are eligible for
http://best.ssa.gov/