We comply fully with Envato’s refund policy. We issue refunds for the reasons Envato permits us to give refunds and we don’t issue refunds on the cases Envato does not guarantee refunds. Please check Envato’s refund policy: https://themeforest.net/page/customer_refund_policy
The payment is one-time. After you pay the one-time price of the theme, you will never be charged for it. But you can buy extended support after your support expires after 6 months.
Yes, you can use all the Home demos on a single website.