Global Product Category List - Dropdown and show empty categories

Hello, for global category list there are limited optional attributes:

[mp_global_categories_list] - Displays a network-wide HTML list of product categories according to preference.
Optional Attributes:
"limit" - Text to display for showing all categories. Default: 50
"order_by" - What column to use for ordering the categories. "count" or "name". Default: count
"order" - Direction to order products by. Can be: DESC, ASC. Default: DESC
"show_count" - Whether to show how many posts are in the category. Default: 0
"include" - What to show, "tags", "categories", or "both".
Example: [mp_global_categories_list limit="30" order_by="name" order="ASC" show_count="1" include="both"]

I would like to know
1. How I can change the list to be a drop-down list
2. How to show only one specific global category and all the sub-categories below it, including the empty ones.

also, I have two more questions that are unanswered from my previous post:

Post here
Thank you