Ih, it look really neat! But it's better when the image is long horizontally and narrow vertically so it would look good in the top of the site without being cropped.

Heres oficial guidance about banners:

https://mlpforums.com/event-team/banner-submissions/

I do! the cutiemarks are especially good though I think they want a banner to be rectangular like how the current one is 

We're desperate for a new banner, any simple kind will do