What do I need to do to preserve the offline maps? Can I backup my preferences and then restore them?
This is indeed an issue, in that even if you are using a backup tool like titanium, it has not protected me in the event of an uninstall/reinstall.
So the question is also, how much customization have you done? For instance, I had many custom map servers edited into NG, so saving my mapservers.txt file would have saved me a ton of work. When you uninstall, the com.neongeo.apps folder is deleted in its entirety so any offline maps, offline data bases, they're all going to go. I have not tried this, but, I wonder what happens if you just rename that whole folder com.neongeo.save, uninstal, reinstall, and then copy all the files you want to retain out of that folder into the live one. I may try this today to see what I get.
BTW, I have been using SAMBA (https://play.google.com/store/apps/details?id=com.funkyfresh.samba
) to move files on and off of my android, and backup files. It lets the android become an SMB file server so that from your PC or mac you can just open it like any file server and navigate to your NG folders. Saves me a LOT of time compared to a USB connection. If I need to move a quick file over I often just use dropbox, but if it is a bigger file or multiple files I almost always launch SAMBA and it works flawlessly.