I'm in the process of updating the website, maintenance, at this stage. Issue #11 is open, for the link to the Maven Repository, it appears to be correct.
No that's a third party site. If we're going to have a link it should be to Maven central. Either a link to all the releases[1] for org.postgresql/postgresql or the latest release[2].
I think it'd be really convenient to have the Maven coordinates for the latest version on the site as well. That way a user can copy/paste it into their pom. Maybe have them in a pre/code block so it's a different font too. Should be easy with the markdown layout for the new site.