for NVC, you only need digital copies uploaded to the CEAC portal.
BUT, for the interview, you will need the originals and original translations of all the documents that are not in english.
You don't need the affidavit of support during the interview as they never asked for it in the past. I always recommend to take the affidavit of support you signed with all supporting documents (tax transcripts and all) to the interview, just in case