random Header Featured Images display

hello again:) i have two questions, which i could't find the answer... 1)can i display a few Header Featured Images randomly? i found that Theme > Customize Header Image make it possible, yet i prefer the design of Header Featured Image... 2) somehow, a black line appears between the category title and post title. like this: http://keyspace.info/category/small-space-case-study/ can i delete the line?? thank you in advance:)