OP here. I totally agree that ideally authors should report most of this information in the paper itself. One advantage of a standalone document (we suggest put

OP here. I totally agree that ideally authors should report most of this information in the paper itself. One advantage of a standalone document (we suggest putting it in an appendix) is that it's easy for reviewers to check that all of this information has been reported. Of course, authors could answer some of the questions by pointing to the sections of the paper in which they have been answered.