Welcome to the forum @brad, thanks for checking out Duplicati!
I’m going to leave the sqlite questions to somebody who knows that area better than I do, but I can answer the last two questions.
There is nothing in the Duplicati folder than can’t be regenerated. That being said, if you lose that folder you’ll have to manually re-create the backup job (unless you’ve exported the config to a file somewhere, in which case you can just import it) and the local sqlite backup database will have to be rebuilt from the remote destination (which can take a while to do).
If you do choose to back up the ~/.config/Duplicati/ folder, note that you may get file access errors when trying to backup the .sqlite file used during the backup process since the file is already open for writing by the backup job itself.
I’m not sure what you have in mind when you say “prior backup status” but at present there are two tools I know of being developed to provide reporting functionality beyond the current one-email-per-job option.
(My apologies to any options I may have missed.)