Yes, our Ultimate Auction Theme Pro is based on WooCommerce  and Advanced Custom Fields Pro. So you can install Themes on the existing WordPress website and start adding auction products.
Make sure to take backup before installing and activating the theme.

Since Theme is based on WooCommerce, there are 100+ payment gateways you can use. Few popular once are Paypal, Stripe, Square, Google Pay, Amazon Pay, PayFast etc. PRO version does have a automatic debit and payment hold features which works with only Stripe payment gateway as its the only one which has rich suite of Developer APIs.

Yes, it does. And we may also let you know that it has anti-sniping feature which extends time if someone bids just before the end time.