Hi,
1. That option is for displaying the column titles on the products listing of the cart, not the module title. That is handled by another option in the joomla option page of the module and the module title is displayed by your template, not by HikaShop, so if that doesn't work, it means that your template does not display a title for modules in the position where you set your cart module.
2. That is also handled by your template, not by HikaShop.
3. You have a good point. That option should not be displayed for the cart module. We'll remove it.
4. It's impossible to say anything about such CSS issue without looking at the CSS/HTML with firebug. Please provide the URL of your shop and we'll have a look.