Hi,
Thanks for the interest in our plugins.
The WooCommerce Tickets plugin setups a special product in WooCommerce for the tickets. It is still a product though so any coupons you can create in WooCommerce will work on tickets.
For your questions on 1 and 3 those are possible in WooCommerce.
I am not sure WooCommerce Supports coupons and taxes the way you describe they would be able to answer that question better then us.
Unfortunately, we do not have an admin demo for our plugins. However, you could download WooCommerce and test their coupons on products and if they work how you would like then they will work on tickets too.
Let me know if you have any follow up questions.
Thanks