global categories and taxonomies

i dont have any product at the main site, all the products are from multisite vendors, so i just need to show global product categories, can i show category count? can i show sub categories with drop down list?
global product taxonomies, product filter, can i show in main site?
i have a lot of filter,
search by brand, size, color, material, gender, price, occasion, country
without filter, there will be over 50,000 products and will not easy for the user to search the product.