You can add this CSS

#page-site-header {
background-size: auto;
background-repeat: no-repeat;
}

The link to the page that you have shared is not found. Is it possible to share a reference screenshot?

Can you please share your site url? and if possible reference a screenshot of the issue that you are facing

we are sorry for the late follow, can you please try adding CSS to Additional CSS in the theme customizer? Here is the code

@media screen and (max-width: 74.9375em){
.wp-block-navigation__responsive-container.is-menu-open .wp-block-navigation__responsive-container-content .wp-block-navigation__container.has-primary-background-color {
background: transparent !important;
}
}

After add its looks something like this
https://www.awesomescreenshot.com/video/19999369?key=8717bd411ecc11ed60cf44ee04c77126

hope its works for you

There is no such option on the theme to change the layout of the header. It is only possible by customizing the theme code. If you really want to change the header layout you need hire a developer who can customize the theme

Yes, there is no options to change the label of search button.

No worries, we can change the label by adding a few lines of JS code

For that you need to install “Simple Custom CSS And JS” plugin, you can follow the screen record
https://www.awesomescreenshot.com/video/19913578?key=9ec7b5ca3282b7a20cce6e95d70ac4ed

Here is the JS code

jQuery(document).ready(function($) {
$( ‘#masthead .search-submit’ ).attr( ‘value’, ‘search…’ );
});

you can change the value ‘search…’ as per your requirement

after adding the JS code published and refresh the site

Please add this CSS in the Additional to hide the post pagination

.single .post-navigation{
display: none;
}

Here is the screen record for how to add
https://www.awesomescreenshot.com/video/19546639?key=e16046ba6c6f9587ba1c9084089b8e96