Yes, the South Carolina Department of Revenue requires you either file 1099 online, or you paper-file.
Yes, but you need to file 1099 directly with the State Department of Revenue.
You must file the required 1099 forms only if there is state tax withholding.
The Form WH-1606 return is the Annual Reconciliation Form and must be filed even if there are no reportable income or taxes due for the reporting period.
The filing due date for both the Form 1099 & WH-1606 is the last day of January.
The state of South Carolina mandates you efile 1099 forms when submitting 250 or more 1099 forms. E-filing is preferred in general, but if you are submitting fewer than 250 1099s you may paper file.