g1smd - 8:33 pm on Aug 30, 2013 (gmt 0)
First you need to get a much newer copy of the basic Joomla htaccess file. Yours is very old and contains several flaws.
Having obtained a new file, you'll then need to customise it with your various changes. However, you need to do it slightly differently.
The rules in your current file are in the wrong order. The new htaccess file available for Joomla gives hints as to where additional rules should go. Follow those directions closely.
The first section should contain rules that block access. The next section should be RewriteRules configured as redirects, with the non-www/www rule as the last one. The final section should be RewriteRules configured as internal rewrites.
The rule order is very important.