If the contracting team has questions about the quote can they contact the offeror for clarifications about the quote before the RFQ closes?
Regarding your basic question, the formalities of FAR Part 15 pertaining to discussions and clarifications do not apply to Part 13 procurements, so I see no reason not to contact the offeror for clarification about a quote. I don't believe before/after the RFQ closing date changes that, as long as the impartiality considerations at FAR 13.106-2(a) are followed and there is nothing in the basic contract to indicate otherwise. As a side note, when using FAR Subpart 16.5, other parts of the FAR such as Parts 13 and/or 15 are relevant too. In this case, you would need to follow the competitive requirements at FAR 13.106-1 if planning to make an award for an item that was not competed.