Garage + storage —>possibly suggest sealers products?

Submitted to Product Chat

Possible product suggestions to help a unique situation?

We have a newly constructed garage (2015) that's made of cinderblock- interior drywalled and painted. 
Most of the garage is above ground and has a side walk out. The back end edge is approximately 20 inches below grade. 
Cinderblock exterior walls are parged and painted.
At the exterior —rear end under the stairs there is an outdoor shower and a elevated deck above.

Problem

Some interior items stored near the back wall ( the submersed part) adjacent to the new electric water heater  ( 2015- does not seem to have a problem) are slowly growing a dusty mold mildew to a small degree. It easily wipes off with cleaner. Theres no water leaks or structural problems other than during rain or snow -water is brought into the garage and seen dripping off the car. 

Additionally we are a waterfront property in a cove and moisture and humidity seems to be part of our microclimate.

I had a LL bean canvas tote bag in a loosely hinge flapped closed plastic bin mold up, along the bottom third border of the ping pong table molds and a small area ( 16x20) of the back dry wall did get a little mold, airflow was blocked by excessive storage. There is some patchy rust on the exterior of the water heater in one area and small amount in tiny spots on the upright freezer front.

We recently open up the air flow this problem area by moving storage around. Hopefully it will help- maybe possibly solve the situation- not sure. 

Question
Garages can commonly can have some moisture -Wondered....how to further improve the situation?  

Are there any Rust-Oleum product recommendations to best seal up our situation from offending moisture to better protect the contents?

Would sealing the underside of the ping pong table to help decrease the porosity of the wood, it looks like a chipped wood fiber product?

Should the interior drywall be protected with a chemical, a sealer or specific wall paint? Or wall paint additive?

Does sealing the garage floor help or hurt the situation? Would a sealed floor cause water to puddle and remain for a longer period after dripping off the vehicle?

Thanks for any helpful products you might suggest. We like to be proactive and take care of our property the best we can, often we cannot keep up with new products and techniques.