Build a Salesforce experience cloud website

We are a ministry with a small website (fulfilledchurchinBoston.org) that we want to port to Salesforce Experience cloud. It is built on a proprietary platform. We want to port the pages using native Salesforce experience cloud as much as possible. We want the contact form on the site to create new contacts in Salesforce. The site has a payment processing component which we want to keep. We'd like it to be as user friendly as possible. We want the youtube videos to be embedded. We want the SEO to remain intact. We want the audio files to stream in from soundcloud. We want to learn how to make page updates on our own after the project is done. Site must be built for both desktop and mobile. Need to then point the existing domain to the newly built site.