If I'm reading it right, it means regular members can now use the PM feature.
I wonder why this wasn't done on the other board. Especially if there are safety protocols to monitor content in PMs.
As for the SA chat thing, Admins have the ability to chat with each other / other members. There's a bar at the bottom of the screen. You see who's online, click on their name, and you can chat with them. If a regular member gets a chat popup from an admin, they can't respond though. If that happens, regular members can now PM the admin, or they can click "send e-mail" and reach the admin that way.