hey i am lauren and have been off for a few days but i wanted to try and answer some of your questions.
the sypathetic block goes into the tier of your back that is involved...i have lumbar sympathetics...in my lower back.
i have had a lot of sympathetic blocks (once a week) and only once did i walk out in worse shape than i went in. the problem with that one was when my meds werent given until seconds before and didnt start working before she started poking me, so all of my muscles tightened and i was in spasm for days after.
the blocks really are the best way to figure out whether or not the problems are related to rsd...and the docs are usually very good at making sure you are comfortable throughout the procedure.