g1smd - 3:22 pm on Nov 1, 2012 (gmt 0)
1. You need to exclude external requests for "/" from being rewritten so that the DirectoryIndex directive can then action the request. Mod_rewrite gets to it first and DirectoryIndex never gets a chance.
2. You need to exclude internal subrequests for index.htm from being rewritten. At present your ruleset only stops requests for index.php from being rewritten (this prevents an infinite loop). If requests (internal or external) for index.htm are rewritten, you'll never be able to access the index.htm file content.
You do not need the
RewriteBase /index.php - looks incorrect too.