Woocommerce category pages

Hello, I have some questions related to woocommerce:

1.- It’s possible to modify the category pages in woocommerce?
I have taken the shop template and change the name to “tienda”. In this page I can add content on top with the template builder and after that the shop part is automatically displayed.
It’s possible to manually modify each template for the categories so I can add content for SEO purposes (at least an H1 tag and some text)

The main shop: In http://prepro.paadonline.org/tienda/
Category 1: http://prepro.paadonline.org/categoria-producto/colchones
King and queen size are categories 2&3

If that is not possible I could create all the category pages by hand and use the shortcode of product grid but I’ll lose the sorting options and I’ll have to make redirects in the automatically pages created by woocommerce to target them to the manually created.

2.- This question is very similar to the previous: It’s possible to create different sidebars for each category page?
In http://prepro.paadonline.org/tienda/ I have 3 categories. I want the navigation and filtering the SAMES but to add unique elements depending of the category. It’s that possible? All the woocommerce category pages are automo

3.- Last question. A black line appears to separate the sidebar and the main area. How can I get rid of this line?

Many Thanks
Jorge