The floor
Epoxy or polyaspartic over a prepared slab. Preparation is the whole job. We grind or acid-etch the slab, fill the cracks, and clean any oil-contaminated area properly. Coat over oil and the floor peels in sheets. A coated floor also stays far easier to keep clean than bare concrete, which sheds dust permanently.
Storage that survives
Mount it on the wall, off the floor. Then nothing sits in water if the slab gets wet, and the floor stays sweepable. Choose steel or coated wire rather than melamine, which swells in this humidity. Overhead racks for the things used twice a year, sized to clear the garage door track.
What garage epoxy flooring depends on
The preparation, almost entirely. Crews grind or acid-etch the slab and fill the cracks. They also clean any oil-contaminated area properly, because a coating over oil lifts in sheets. On a prepared slab it lasts for years, and stops the permanent dusting bare concrete produces. On a dirty one it fails within a season, whatever the product.
Heat
An uninsulated west-facing garage turns brutal by mid afternoon. An insulated door and a ceiling fan make it usable. But if it needs to be genuinely comfortable, that is a conversion rather than an organisation project.