Bram, I will forward your second question to our web designer

However what do you mean by 'how do i manage it that it will show up in the normal menu?' Give us more details plz

Hello

this is the CSS code you add in  theme options -> styling options -> custom CSS to have the menu bar transparent

.page-template-default header, .page-template-default #header-container, .page-template-default .hamburger-rotate, .page-template-default .hamburger-rotate.is-active {
background-color: transparent;
}

.page-template-default #hero [
height: 100vh !important;
}

regarding the picture: you cannot have a fullscreen image without cropping

the solution is to have the image contained (to see the whole image without cropping, but with margins):

.page-template-default .hero-image {
    background-size: contain;
}