[Brad]

What has been the learning path for some of the existing devs here on vbulletin.org?

My advice;

1) Get a decent editor for php, I use Editplus.
2) Start reading the vBulletin source code from 'top to bottom'. IE; Open /forum/index.php in your editor, and open any files that it needs to function (you can find these in require_once().

Some people will say the above is ass backwards, but most of these people already know what is going on in the code or understand the logic because they know another (similar) program. If you're new to this I think going this route will help. For example index.php requires the file global.php so it can function, likewise global.php depends on init.php and a bunch of other files. However we don't need to know global.php, init.php, functions.php or datamanagers like the back of our hand if we want to write simple modifications to index.php (although it is a good idea to know how these files work, I think it'll be too much for you to take on all at once).

Don't worry about coding standards or datamanagers at this point. Just read code, read all the code you can, try to understand what it's doing and how it's doing it. In other words you need to get in the proper mind set!

Also don't think of the code in vBulletin as 'proper' code. Learn from many sources by downloading open source php projects.