When I say point to I mean configuring AOLServer on that box to
connect to to Box 1's Postgres database rather than the one on localhost. In
this configuration only the database on Box 1 will get updated. That is why
the backup to Box 2 is needed.
It can serve pages if you want it to if they are using the same database. Also
you can make sure you connect to it to send out your mailings. The mailing
work will be done by Box 2 but it will still use the database from Box 1.
And yes, more frequent backups means you'd lose less data in case of
catastrophe.