Custom Template with Variable Content Box and Stylesheets

Hey, sorry if this is the wrong place to post, however I’m new to WordPress and was wondering if anyone could help me. I’m designing a website and wanted to know if it’s possible to, firstly, have a pre-designed content block (section), with all the elements inside editable, and have it so that you can add/remove sections as needed, and be able to edit all the content inside using the WP customiser.

Secondly, I wondered if it’s possible to have all these sections stitched together scrolling on the right side of the page, whilst having a static left side of the page with a nav menu and a “quote”, which changes based on the section in view. So when “section-x” reaches the top of the viewport, the quote changes to the corresponding quote entered under the settings for “section-x”, and remains until a new section comes in and takes over. Similarly could this be done with different stylesheets for each section, which changes the background and font colours each time a section becomes in view?

I’ve added a quick sketch of what I’m talking about, and would love to know any resources there might be on this, the difficulty of it, and perhaps how long you think it would take an expert to build this functionality, while not worrying about the CSS formatting.

Thanks in advance,
Sam