Your powerpoint presentation is very cool but you are still thinking in “old” website design of your other website where you had limitations. I know, I use to have a sitebuilder website.
With WP you have so many options, oh so many. Customizr free template (open source) is an example of Header, Body, Footer, Sidebars on right and left. Each page can be configured differently with the exception of the Footer, which is on every page always.
So the Header can be different, the sidebars can show or not. Once a sidebar has info in it, like a menu, that info cannot change page by page, but you choose to show the sidebar or not on specific pages. My sidebars, when I used Customizr, were filled with advertising for the most part.
Share – icons in the body are clickable for your visitors to SHARE that particular page with THEIR social media friends.
Follow on Social Media – icons are clickable and will take your visitor to your Facebook page or Twitter or LinkedIn or Instagram.
The red button in the header of Customizr “contact author” can say anything (click here to buy, send ed a message, for example) or gone and can be different on every page. There is room in the header for 2 lines of text too.
I can put in a simple paypal cart, exactly the same one you used to send me $250 via paypal. It is a plugin, it is free, it is simple and you will be able to add product and make changes to prices or description, etc. Configuring it to go to paypal and testing it to see if it works takes some time, but adding a product or changing a price is right here in your WordPress website.