PIP

On your menu page in the WP Admin, in the upper right corner you’ll see “Screen Options”

Click that and then check “Product Categories”

So you can pretty easily do this by setting your homepage to your shop page in:

Settings > Reading

Then click the radio that says “A static page”

Then for front page choose your main shop page.

And finally add this code to your functions file:

/**
 * Change number of products per page
 */

add_filter( 'storefront_products_per_page', 'sf_child_products_per_page' );
function sf_child_products_per_page() {
	return 99;
}

Where 99 is the minimum number of products that will show per page. So set that to 99 or 999 or whatever is larger than the number of products in your store.

On line 382 of your style.css file for the boutique theme change where it says “block” to “inline-block” like so:

.page-template-template-homepage-php .boutique-featured-products .storefront-product-section ul.products li.product .price span {
    display: inline-block;
}

On your secondary menu you could try adding the css for horizontally displaying it:

.your-secondary-menu li {display: inline-block;}

You’ll have to change the class: “.your-secondary-menu” to the class of your secondary menu

But hard to know exactly what you’re trying to do without exact images.

Better yet you could just change the template to “Full Width” on your main shop page.

Edit*

To remove the sidebar from the rest of the WooCommerce pages you can add this to your child theme functions file.

remove_action( 'storefront_sidebar', 'storefront_get_sidebar', 10 );