Can flood vent openings be installed in breakaway walls in the hope that flood water forces might reduce the risk of wall collapse? Does the one-square inch of net opening for every one-square foot of net opening apply?

TB-9 (3.3): The 2015 and later editions of the IRC and the 2014 edition of ASCE 24 require flood openings in breakaway walls in both Zone A (including Coastal A Zones) and Zone V. Breakaway walls with flood openings must be designed to fail under the base flood specified by the NFIP regulations and building codes and standards. The NFIP regulations do not require flood openings in breakaway walls of enclosures below elevated buildings in Zone V but require flood openings in walls of enclosures below elevated buildings in Zone A, even when breakaway walls are specified. See NFIP Technical Bulletin 1, Requirements for Flood Openings in Foundation Walls and Walls
of Enclosures.