1) OK, the thing you have to understand about setting the background-image property of an object (in this case, the site-header link) is that for background images, the image will only be as big as the container, and the container will only be as big as the objects that it contains (unless it’s a block level element, in which case the width will stretch across the width of its containing element by default).
So, even though you made the text color for “My Next Pad” transparent, the container (the anchor tag) will still be big enough to hold the text.
You can see what I mean by temporarily making the text visible by setting it to red, then adding a font-size to this rule in your child theme’s style.css file:
.site-header h1 a {
background-image: url(http://www.mynextpad.co.uk/wp-content/uploads/2014/08/mynextpadlogo-441x89.png);
background-size: contain;
background-repeat: no-repeat;
color: red; /* changed from transparent */
line-height: 80px;
font-size: 80px; /* make font bigger */
}
You’ll see that if you adjust the font-size up or down, the background image will also grow or shrink, because the container will adjust to fit the text that it contains.
So, there are a couple of ways that you can make the image bigger. You can either set the font size of the text to some large value so the container grows big enough to the size that you want, or you can explicitly set the size of the container using the width property. The logo image has a natural width of 441px, so you can actually just modify the rule to set the width of the container to match the size of the logo:
.site-header h1 a {
background-image: url(http://www.mynextpad.co.uk/wp-content/uploads/2014/08/mynextpadlogo-441x89.png);
background-size: contain;
background-repeat: no-repeat;
color: transparent;
line-height: 80px;
width: 441px; /* set width of container */
}
2) Yes. The body element on the home page will contain a class called (appropriately) home, so by including it in the selector of whatever CSS rule that you create, the rule will only affect elements on the home page. So what you should do is hide the header by default, then add a rule that displays the header if it’s on the home page:
/* hide header by default */
.site-header {
display: none;
}
/* display header on home page */
.home .site-header {
display: block;
}
3) Make a copy of the parent theme’s footer.php file into your child theme folder, then substitute the part of the code inside the site-info div with your copyright info. That is, change this:
<div class="site-info">
<?php do_action( 'twentytwelve_credits' ); ?>
<a href="<?php echo esc_url( __( 'http://wordpress.org/', 'twentytwelve' ) ); ?>" title="<?php esc_attr_e( 'Semantic Personal Publishing Platform', 'twentytwelve' ); ?>"><?php printf( __( 'Proudly powered by %s', 'twentytwelve' ), 'WordPress' ); ?></a>
</div><!-- .site-info -->
to this:
<div class="site-info">
Copyright 2014 My Next Pad
</div><!-- .site-info -->