Hello,
1) I removed doubled default header. Also, we have fixed the double default header issue a few updates ago. You should face this problem anymore in future.
2) Read more here about mobile header https://www.8theme.com/topic/cache-mobile-shop-filters-display-at-the-bottom-of-the-page-instead-off-canvas/ I have installed the mentioned plugin on your site. Check it now.
Regards
