Hi,
Thanks for the interest in our plugins.
You do not need to purchase Events Calendar Pro to use WooCommerce Tickets.
Each of those plugins only needs the core version of the Events Calendar. ‘
If you would like both plugins you have to purchase both of them.
We do not have any features to modify the checkout of WooCommerce, but you could a plugin such as WooCommerce Checkout Manager:
Checkout Field Manager (Checkout Manager) for WooCommerce
To modify it.
Let me know if you have any follow up questions.
Thanks