Your rewrite rule is wrong. The existing rule is for when the site is at root– http://localhost. You site is at http://localhost/highimpact. The final rewrite rule should, I believe, RewriteRule . /highimpact/index.php [L].
If you go to wp-admin->Permalinks, and save the settings WordPress will rewrite the rules or tell you what the rules need to be if .htaccess isn’t writable by the server. Try that, in case my guess is wrong.
I don’t know what needs to happen with the cache rules. I would guess that the cache plugin has a similar mechanism for rewriting its rules but I don’t how to get there.