You can go for a commercial package such as Zend ide with full profiling and debugging support I have used it and hated it. Komodo is another I have looked at but not been overly impressed, its syntax highlighting colors are a mess and could not be changed in the version I tried.
I would recommend eclipse, it is an open source ide (integrated development environment) that supports many languages via plugins. I use it for php and C, C++ development.
You will need the following
Eclipse
Php eclipse plugin
QuantumDB plugin multiple database support
Some screenshots of my environment
Syntax highlighting
More syntax look on the right for the outline of the document, public variables in green, private in red, functions used etc.
Quantum DB in use
Install eclipse, then phpeclipse plugin, then quantumdb, if you install quantum before phpeclipse theres bugs but they may have been ironed out by now.
For debugging you can integrate dbg but I never use it as I dont write applications large enough for it to be of use. You are better learning to write php test driven design code with something like
phpunit
Download and install, I think you will be pleasantly surprised by its power.
Hope that helps.