Hi again.
About the privileges, our support can create roles / databases, drop existing databases, dump /restore, change other users passwords. It's not feasible right now create a 1:1 map of system users and postgres users. Maybe in the future.
I wrote 2 possible patches, both issuing a detail message only if log_connections is enabled.
The first one using the Stephen Frost suggestion, inside the Port struct (I guess that this is the one, I coudn't find the Peer struct)
The second one following the same approach of cf commit 5e0b5dcab, as pointed by Tom Lane.
Again, feel free to comment and criticize.