WordPress from the ground up

Introduction

I have been putting some time aside to learning WordPress recently, in the the past I have had to do little bits and pieces on WordPress sites or a fiddle with something that doesn't quite work on a site built by someone else on top of a specialized theme that has been purchased. I wanted to learn how WordPress works from the bottom up.
I also want to get a feel for how much customization is possible and the feasibility of using WordPress as a development framework. I have a personal project in mind that theoretically I could build in Drupal, however Drupal is a bit weighty for what I want and a WordPress based project should be much easier for people to set up and install.

The site

The best way to learn is by doing, I built a theme and site from scratch, starting with empty files. Despite being graphically challenged and design challenged (I am clearly not a graphic designer ;)) I want to do a bit more of this type of thing just to understand the process and the challenges etc. Originally I was aiming to produce a responsive layout but that just added too much to the mix, the mechanics are one thing but working out how to design for it (I did mention I am not a designer at at all didn't I?), working in an unfamiliar environment etc. was took much in the time I had.
The next problem was content, normally I have been using Blogger for blogging, if I want to write something I just write it and not being commercially orientated, or traffic dependent it doesn't take up too much of my attention. Now I still haven't enough content to structure the blog the way I want to.
The blog is about the Raspberry Pi and my experiences with it at raspberry-fool.com Still lots to do, adding links, news items more static pages, Disqus comments etc. but I will just do a little every now and again a build it up. I am taking the time to play/experiment with plugins etc., working out how core code works and how the whole picture fits together.
I am fully aware that I could get a better WordPress blog up and polished off in less time, picking one of the many themes available, working through one of lists of recommended plugins. But then I would be working from the outside in, and learning a lot less.

Some observations

WordPress has more potential than I expected, soon I hope to find something I want to do that requires me to write a plugin (I have been reading about the process and investigating code but got beyond the theme) and then I will know for sure, but looks like I can build my application on to it.
.
Right now I am preferring the hook system in WordPress over Drupal, you can register and de-register functions against hooks.
Not sure whether I prefer it or not but interesting that in WordPress if I don't provide a template for something, in many cases nothing is displayed. There are some defaults but not so many as Drupal. At least this quickly shows me the areas where I need to work on something.