to make that textdomain, is that done via any other function or is it just taken from the name of the theme
In order for people to be able to use their own language files, you have add something to functions.php. I typically use something like:
load_theme_textdomain( 'collage', get_template_directory() . '/languages' );
$locale = get_locale();
$locale_file = get_template_directory() . "/languages/$locale.php";
if ( is_readable( $locale_file ) ) require_once( $locale_file );
but that won't affect the generated markup in any way. Listen to chreo. He(?) has a good point. If you have not set up a custom menu & assigned it to your Primary location yet, your theme/site will be using the default fallback - which is wp_page_menu(). That has its own, independent, parameters and generated output. wp_nav_menu's parameters only kick in when your custom menu is being displayed.
The bad news is that there isn't a parameter in wp_page_menu to remove its enclosing
<div></div>. The good news is that you don't have to fallback to wp_page_menu. You could use (say) wp_list_pages() or something else entirely. You can specify exactly what function what you want to use via the
fallback_cb parameter in wp_nav_menu().