I'm trying to learn WordPress best practices.
You will not learn by trying to build a Ferrari as a first project.
Small is better, start with a starter theme like a twenty eleven child theme.
Find tutorials that change the default theme, then learn how to code and style WordPress, take time and learn, download themes that have some of the features you want and copy the code snipits and styles across.
Once you have learnt a bit then plan your own theme, draw it out on paper, decide what can be done with a widget and what you need to code.
Build your theme in small steps, as you complete each step it will feel good, try not to build the whole site in one go it is likely never to be finished.
Understanding the template hierarchy and the WordPress Codex is also important.
Who knows in six months you might be back showing us your Ferrari!
I have a few child themes that have little changes, these might get you started, as a child theme only has the changes and not all files!
This code an answer for another toipc here, is an example of muliple loops.