I have a plone zinstance set up through Apache Proxy on OS X Server 10.5. The server is set up with a single vhost on port 80, with Proxy & Proxypass directives to the Plon
I'd recommend rolling your configuration into a virtual host block. You can deliver static content directly form apache by rewriting a specific path. Here's an example
ServerName yoursite.com
Alias /static /var/www/some/path/
Options Includes FollowSymLinks
AllowOverride All
# Zope rewrite.
RewriteEngine On
RewriteRule /static - [L]
RewriteRule ^/(.*) http://127.0.0.1:8080/VirtualHostBase/http/%{SERVER_NAME}:80/Plone/VirtualHostRoot/$1 [L,P]