Hi there,
Here are some element of answer, however, a link to your website would have been helpfull to be more precise:
1. Theoretically the rows should use whole space, try to look with firebug if there is anything in this space, maybe an empty you forgot to delete
2-3-4-5-6-7. Actually for these question you always have to follow the same process. Let's take an example with your second question. Do a Right click on the link and open firebug (or "examinate this page") to look at the class which include the link. You'll see it's hikashop_cart_module_product_name_value hikashop_cart_value . Then edit your frondend css in System>Configuration>Display. In this case you'll have to add something like:
.hikashop_cart_module_product_name_value hikashop_cart_value a{
color:red;
}
the "a" added at the end of the class specify the element on which your rule will be added, in this case, the links.
Just try it by yourself for your other question. If you really can't achieve what you're looking for, I'll help you but you may understand that we don't have that much time do that kind css customization.
8 - Try to update, we have changed few things in the social plugin and it may solve the problem
.