IAW FAR 16.506(a), your basic IDIQ contract should include the clause 52.216-18, which states " Insert the clause at 52.216-18, Ordering, in solicitations and contracts when a definite-quantity contract, a requirements contract, or an indefinite-quantity contract is contemplated."   

Specifically, paragraph (b) of the clause says "All delivery orders or task orders are subject to the terms and conditions of this contract. In the event of conflict between a delivery order or task order and this contract, the contract shall control."   So the clauses in the basic contract indeed flow down to the delivery orders.  You can add a clause to the delivery order as long as, 1) it does not conflict with the basic contract, and 2) the contractor agrees in the form of a bilateral modification.