I'm actually not sure why that 1 is there. I just used the default ID editor interface. I don't recall adding a 1, so I'd imagine it's just a quirk of the editor that has since been updated. In any case, it should be safe to remove.

There was indeed a typo! I was able to verify the roof shape using alternative aerial imaging. The new change-set number is 146763376

This building doesn't exist as mapped. I've removed it and replaced it with the actual buildings present at this location.

It is indeed a typo. Good catch! I fixed the issue in a separate changeset. (113253583)