1) Hope the footer issue have been resolved.
2 ) Do you want to customize the category page sidebar content ? then get into Admin Panel > Appearance > Widgets > there you can add more contents.
Refer : http://prntscr.com/gk5u8z
Else if you want to add a page content means, sorry as of now you can’t add more contents to the category archive page.
3 ) Get into the file path /wp-content/plugins/designthemes-core-features/languages there you can translate the text.
Refer : http://prntscr.com/gk5q9e