The way I've transitioned between languages was to first do a syntax comparison: http://merd.sourceforge.net/pixel/language-study/syntax-acro...
Then take a crash course: http://cs.metrostate.edu/~fitzgesu/courses/ics325/summer04/C...
Then learn about database interfaces: http://www.kitebird.com/articles/php-pdo.html
Then learn about programming patterns: http://www.rosettacode.org/wiki/Category:Solutions_by_Progra...
Then learn about security: http://www.owasp.org/index.php/PHP_Top_5
Then learn about error handling: http://www.w3schools.com/php/php_error.asp
Then learn about debugging: http://www.onlamp.com/pub/a/php/2004/08/12/DebuggingPHP.html
Then learn about idioms: http://www.cybersprocket.com/wiki/index.php/Eric's_PHP_Guide
Then read a comprehensive book: http://www.ubookcase.com/book/Sams/PHP%205%20Unleashed/
Then learn about optimization: http://progtuts.info/55/php-optimization-tips/
I've used PSPad, Komodo Edit, and Aptana Studio Community Edition for PHP editing, and recommend them all.
I've tried CakePHP and Drupal, but had trouble with the documentation and syntax of both compared to pure PHP. Wordpress has great documentation, community support, and readable sourcecode.