sidebar align on top and some other questions

Hi i’ve changed some stuff in my side bar. But the images keep falling down (don’t stay at the top) where do i edit this? https://www.pimiento.nl/wordpress/

Also in my header a bit of the image falls out (don’t know how to explain) how can i change this?

Finally what are the ‘crosses’ in Meta en in the left corner of the header image?

Thanks in advance for any help!