I'm aware that Save Image in Folder and Save Link in Folder are no longer compatible with the latest Firefox releases.
These extensions are based on Mozilla's XUL- and XPCOM-APIs, which are now obsolete and no longer supported.
Bringing the extensions back to life would require a complete rewrite using WebExtensions.
Unfortunately at the moment I can't give you any details on when (or even if) I will be able to accomplish this task.
I will look into it if time permits.
Yes, there is. Like pretty much every other extension out there, SLiF/SIiF saves its preferences directly into Firefox's preference-system. Just open Firefox and type "about:config" in the address-bar. Then type "extensions.savelinkinfolder" (or "extensions.saveimageinfolder") into the filter-box. You then should see all settings for SLiF/SIiF. Just copy the preference named "extensions.savelinkinfolder.folders" (or "extensions.saveimageinfolder.folders") into a text-file. Now you have exported your folder-settings. Later on you can use this method (the other way around) to import aswell.