You must have an early altskin_common.php
If you don't use the addons, either comment out the code, or apply the relevant SQL patches to stop errors. Most people are using them.
You can use a separate database for WP if you wish, same goes for the reBOOT template.
Get your client to drop me a line and I'll send details.
Regardless, Wordpress should always be
locked down and you must be wary of
plugins.