can creditors go after social security and private pensions to settle a debt?

Answer 1

SS is not touchable except for student loans but you can have pensions or bank accounts used to pay your debt.
If you have direct deposit of your SS and it isn't alone in the bank account they might not be able to tell what money they are taking.

Answer 2

Supreme Court: Unpaid student loans can be withheld from Social Security
http://www.post-gazette.com/pg/05342/618941.stm