You should be able to use 1 database for multiple sites already. There is a database setting to allow remote connections and just use the same database server in your connection.
We probably won't allow direct php coding in the cms..there are just too many ways that could break things.
The largest changes are mySQLi support and improved email functionality.
Database remote access is a setting in the database itself. Talk to your hosting provider and they will be able to tell you if they support it and how to set it up.