Hey,
You’ll want to use the custom taxonomy tag %%ct_desc_<custom-tax-name>%%
So you’ll end up with %%ct_product_brand%% %%title%% %%page%%
Source: http://kb.yoast.com/article/146-yoast-wordpress-seo-titles-metas-template-variables
Yes but you need to make sure your custom post type is hierarchical.
When registering your CPT make sure to set this param as true:
'hierarchical' => true,
By default this is false for custom post types
