The next version will disable auto-sort by default. The "about:config" settings are not used. You can just manually delete them. I don't think there is an API to remove them under the WebExtensions API, but I'll check.
1) You don't need any add-on to sort a specific folder. Firefox already does this.
2) Yes, I'm working on the "Exclude Folders" option, but it requires a re-write due to Mozilla removing the bookmark tag feature under WebExtensions.