Hi Eh,
Welcome to Auctiva!
1) We don't offer any functionality that can be used to automatically send your buyers emails once they have paid, but you could potentially create a custom email template and for that purpose and send the email out manually when your buyers complete the process of paying for your items.
If you create a custom email template with a message you would like to send to your buyers once they have paid for the items they purchase, you could then send that email by clicking the "Transactions" link under the Sales tab within your account and selecting the "Email Buyer" option next to the item. You will then need to select the "Email Type" that you classified the custom email you'd like to send as and you'll see the option to send that email.
2) If you are selling two different types of items, you should actually be able to use the same email template for both. When you create a custom email template, you can use the buttons in the "Item Information" section to add tags to your email template that will be replaced with that information specific to the item in question when you send the email template to the buyer of an item.
If you have any additional questions regarding your Auctiva account, please feel free to contact our customer support team using the web form on the following page of our site:
http://www.auctiva.com/help/requesthelp.aspx-Mike