Portfolio thumbs e slug

Hello,
I have a problem with portfolio.
In this site: http://progettiverdi.sitowebwp.it/portfolio/ in themes setting I set Full Width portfolio but the images are very small. The image are 600×600 px
In themes setting I set space 2 and the space in right and left are very big. Why there is this space between image?
I set 3 cols but with firefox I can see 2 cols for the space problem.

For the slug in function child theme I set slug progetti but I see always project in breadcrums http://progettiverdi.sitowebwp.it/portfolio/

Can you help me please?
Thanks
Cristina

//Rewrite Custom Post type “portfolio” to “my_slug”
add_filter(‘register_post_type_args’, ‘portfolio_to_my_slug’, 10, 2);
function portfolio_to_my_slug($args, $post_type){

if ($post_type == ‘portfolio’){
$args[‘rewrite’][‘slug’] = ‘progetti’;
}

return $args;
}

I attach the image