eBay Shipping and Payment Details pertains to eBay's checkout. On an eBay listing, it will be after your description in a Payment Details section.
If you're using Vendio Checkout then you wouldn't want to activate this option. Unless you are planning to use Checkout Redirect. As long as you have your PayPal email address stored properly in Global Preferences and you check off any Post Sale Acceleration options in My Account > Post Sale Acceleration, your payments will appear on PayPal with the right shipping and will automatically record in your Vendio account when a customer pays you.
The FAQ has more information about eBay's Checkout and Vendio Checkout, in case you need to read more information on this.
As always, if you need more help please feel free to ask.
Unfortunately I don't have anything more for you on eBay Checkout -- I apologize for that. However you can set the defaults up in My Account > eBay Site Specifics. If you have more questions about it feel free to ask me.