Hi, please find below the answers:

– it’s not recommended to replace CSS class names and script variables. But if you have to replace then same replacement should be done in respective theme/plugin’s css file as well.
More info regarding replacement – http://codecanyon.net/item/hide-my-wp-no-one-can-know-you-use-wordpress/4177158/faqs/20827

– it could be detected as WP site if there’s some comment added by plugins in the site’s page source. You’ll need to remove/replace these using HMWP’s “replace in html” option.

– with HMWP you can only secure login url by adding a secret key to it (e.g. http://www.yourdomain.com/wp-login.php?hide_my_wp=1234). If you want to change/rename the login url then you can use plugin like Theme My Login.

– the website url live.classe.com doesn’t work ?

Replacing css class names like wp-submit, sidebar-wp-submit, wp-post-image, etc, might break the site. It’s not recommended to replace these, but if you want to replace then you can do the following (needs little bit of programming knowledge):
– add replacement in “replace in html” like wp-post-image ==> my-image
– copy the css content of .wp-post-image{} from the respective css file and add it to your theme’s style.css as .my-image{}

Regarding the login url being shown in source code, please check this FAQ – http://codecanyon.net/item/hide-my-wp-no-one-can-know-you-use-wordpress/4177158/faqs/15899

And wordpress might have been detected because of wp-login.php in the site’s page source. You can change the login url path using Theme my login plugin as described in FAQ above.