Total cost of ownership - yearly

I want to start with a disclaimer: I am not a technology person to understand the technical lingo. I am end user with usual technology exposure looking to setup a website for a start-up idea. While the products/services offered by envato look impressive there is some clarity that is required around some points.
Is it possible to get an idea of total cost of ownership for a product. Say I start from ‘Listify’ theme and plan to undertake a typical route to get my site to market. Right from selection of template, customizing by adding pictures/texts/data, adding typical ecommerce features, hosting, buying a domain name and ongoing support. What is a typical laundry list of things that need to be done and what out of these are payable (one time or monthly) and what are free. I can understand that this depends on type of product/features/etc … etc
But I am just interested in a typical case study - an example (great if it can be a final product that is live in market) with an imaginative product.

I am also not clear in terms of what it exactly takes. I mean if I buy the ‘theme+hosting’ is there a mandatory minimum period of contract (like a year?). While there are some things that are mentioned on the site, I am wondering what all will not be there.

Also once a person chooses to go with envato hosted service and domain name, who has the ownership of the domain if one day the person chooses to stop envato support (month service?)