Advice concerning lay-out homepage
I would still use blocks for this, because I always prefer to use the most appropriate and lightweight solution for the data storage, and then tweak the admin interface to enhance usability.

You could solve this with a special content type, combined with views or display suite. However, experience has taught me that if you're creating a content type for a small, fixed number of nodes, it usually means that there are better solutions out there.

You are right that the blocks page is too complex for many users. To solve that problem, I would:


Create the 3 blocks;
Enable the Contextual Links module (part of Drupal 7 core) to provide edit links on the blocks, right there in the front end;
Install and configure Block Access to make only those 3 blocks editable by the site maintainer;
Implement hook_form_alter to hide specific form fields from the site maintainer on the block edit form.