I cant answer your questions with any confidence as I'm not a boat guy.
For any fish only pump in fresh water when lake surface water temperatures are below 75 degrees dont pump in hot water from the lake. Drain half of the livewell water every three hours to remove toxic waste products (carbon dioxide and ammonia)
Castnet world makes a product for shad and herring called shad keeper for your livewell. $12.99 treats 100 gallons.
SHAD KEPER (TM) for use with FRESHWATER Shad and Herring and conditions your live bait tank.
SHAD KEEPER (TM) is a complete formula, nothing to add or mix! Helps control toxic ammonia,
removes chlorine, stimulates natural slime coat, hardens scales, enhances oxygenation and
keeps live bait lively and frisky.. Shad and Herring do best in round bait tanks.
Perhaps a move to the South Carolina forum can prompt a more competent and experienced response.