On preserving dried ginger Based on my reading, preserving dried ginger is the same as preserving fresh ginger I.e airtight and in the fridge.
Is there anything more that can be done to preserve the dried version.  After dehydrating it, will not grounding it immediately and instead grounding it at the point of use make a significant difference?
Dried ginger can be kept at room temperature, in any cool dark place (like your pantry), for months to years:

Dried, ground, or crystallized ginger should be stored in a cool dark pantry in a sealed container. Spices with the moisture removed do not really go bad (unless they get wet), but they lose their potency over time and will no longer add flavor to food. If the aroma is gone, the flavor is most likely also gone from the dried ginger.

That's the whole point of drying it; so that it lasts longer without refrigeration.