jdMorgan - 12:18 am on Mar 18, 2011 (gmt 0)
If the "default domain" was configured separately under the control of your hosting company, then the easiest thing to do might be to request a copy of the VirtualHost section their default httpd.conf file -- the one that they used to configure your "default domain." Then modify it as you wish.
It looks like the set-up for scripting support is missing from your custom config file, and very likely there are other things missing as well.
Also, consider moving your .htaccess directives to a <Directory /> container in httpd.conf once you get them debugged -- there is a sometimes-quite-large performance advantage to this, but comparatively few webmasters have this option because they don't have server config access and so are forced to use .htaccess. Directives in config files are "compiled" once at server restart, whereas directives in .htaccess are "interpreted" for each and every HTTP request to the server. A comparison with a pre-compiled "C" executable versus an interpreted PERL script would be fair... Also, if all .htaccess directives can be moved to a config file, then you can use AllowOverride None. Then no per-request directory-walks will be required, and no .htaccess files will be fetched -- a further performance improvement (and reduces disk usage as well).