Number of items and custom archive pages

The following code shows the archives in grid.

	add_filter('avf_blog_style','avia_change_tag_blog_layout', 10, 2); 
	function avia_change_tag_blog_layout($layout, $context){
	if($context == 'tag') $layout = 'blog-grid';
	return $layout;
	}

	add_filter('avf_blog_style','avia_change_category_blog_layout', 10, 2); 
	function avia_change_category_blog_layout($layout, $context){
	if($context == 'archive') $layout = 'blog-grid';
	return $layout;
	}

The default is 3 columns and 10 items.

1- How to modify that to my needs? For example 18 items in 4 columns.

The custom archives I mean to create a layout for them.

2- How to create a layout using the builder, for category, tag, etc…

Those are the 2 things I need to fix.

Thanks.