for the picture accessing on apache..
you can create a .htaccess file and store it in the root directory of your website.
Code:
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^http://(.+\.)?mysite\.com/ [NC]
RewriteCond %{HTTP_REFERER} !^$
RewriteRule .*\.(jpe?g|gif|bmp|png)$ /images/nohotlink.jpe [L]
Stop Hotlinking with htaccess. Test your Image Hotlink Protection with our Hotlink Checker from altlab.com.
plus as ran_dizolph pointed out, create an index.php file and drop it into your image folder. Have index.php redirect users to the home page.
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As for uploading bad files, this is a different issue all together.