If I purchase an HTML ecommerce theme, how easy is it to set up and do they come with a payment and order system?

I was thinking of buying one of these three templatesaahatanadiquinto . I already have a webhost and domain, and have knowledge of html, css and javascript. I was wondering how easy it would be to set up a template without wordpress as ive never purchased a template before, and since it is ecommerce, do these come with order and then payment systems. I have an SSL cert for my site.

In short no - HTML templates are exactly that and don’t include dynamic commerce functionality eg payment, customer profiles, stock management etc.

They can be used to integrate with commerce but you are likely to find it easier to purchase an ecommerce template or theme (doesn’t have to be WordPress, you could look at Shopify, Magento etc.