Hi,
1. That is correct, but you can still enter it there. The plugin only shows the items there as “hints” (that already exist in the database), but you can enter any field name there you want.
2. You have an inclusion set to include posts only from the “Uncategorized” category, which is empty. If you remove that, the results will start appearing.
3. I can confirm, that this is a yet unknown bug. I have made a small edit on the plugin functions.php file to correct that, it should be all okay now. I will include this fix in the next release of course.