Hi,
1 - You can increase the category width/height by modifying/overriding the HikaMarket CSS.
#hikam_category_listing div.oTree, #hikam_product_listing div.oTree {
width: 150px;
overflow: auto;
height: 100%;
}
2 - You can hide (so disable) the "hide button" using CSS or by overriding the view "productmarket | listing".
You can use the id "category_explorer_btn" for hiding the bar itself.
For the overriding of the views, by removing the link, it will disable the feature.
3 - To change the top buttons, the best is to override the view "productmarket | listing".
At this moment you can choose the columns you want to show, change the order, add new columns if required, etc.
Regards,