I got into PHP by way of Drupal. I tend to think of myself not as a PHP programmer, but as a Drupal programmer who is therefore stuck with PHP. I don't work with any other PHP frameworks; If I wanted something that wasn't Drupal I'd be using Ruby.

Now that my biases are clear: You should take up Drupal. It's a big system with a lot of architecture, but the core is not too big; it's being hacked on by many thousands of people and is continuously evolving as the community learns; and it hits a sweet spot between being well architected and being open to the kind of simple cut-and-paste anarchy that makes PHP thrive -- it's designed to let you obsessively customize everything, but it tries to encourage you to contain your creativity within pluggable modules that can (at least in theory, but often in practice as well) be manipulated by noncoders.

If you want to try Drupal and you are a coder you must read VanDyk's Pro Drupal Development, Second Edition ASAP. Trust me on this.

As for Javascript, which is arguably more important: jQuery, jQuery, jQuery. Also: Douglas Crockford, Javascript: The Good Parts. And learn your CSS if you haven't already; I did that by reading Eric Meyer's O'Reilly book, followed by Dan Cederholm's book.