Here's the last info I have on S. Carolina-
They do tax retirement income at a rate of 2.5-7%. You reach the 7% level if you have an income of $11,780 or more.
You get personnel exemptions of $3000/person under age 65, and $10,000 over 65.
This info may have been updated in the last couple of years, so don't take my word for it.
Here's a website that has lots of info:
http://www.taxadmin.org/fta/rate/tax_stru.html
Others will have to help you with the rest of your questions.