Yes, view the offline list. Then tap the ... button and choose "Add to List". Choose the caches you want then at the top switch to "Online" where you can save the caches to an already created list or create a new one.
You can either save them to an Online list which is saved to geocaching.com and can be accessed on both devices. Or, you can export a GPX and import that into your iPad.
Move would move caches from one list to another, just like moving files from one folder to another on a computer. Merge will do the same thing but remove the offline list that the caches were moved from.
This is done by tapping the ... then choosing Sort. This will allow you to drag the lists in a different order or use the sorting options.
This means there are more cacehs to load. If you don't move the map, and continue to tap that button, it will load more and more caches from your initial search.
In your specific case, I am not sure. Offline maps are the only thing that would take up that amount of space. The last resport is to delete Cachly and install again, making sure to backup your offline lists.