Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
PHP.net is a nice place to start with documentation and lots of useful stuff.

To get PHP running smoothly on your Mac (along with MySQL) you can try MAMP. (If you only need PHP your Mac supports that out of the box, but you'll need enable it.)

Also, I've moved this thread to the Web developer forum. Check out the stickies for tips & tricks... :)
 
If you want to learn the language, w3school is your bet. If you want a book, I suggest PHP and MySQL Web Development Forth Edition.

If you just want a server up and running, I suggest MAMP. It's a very good development environment and has Apache, PHP & MySQL (The database you're talking about).

If you just want software to develop PHP on, I suggest CODA but any text editor will do. Text Wrangler is a very good free alternative. CODA has FTP (Transit), so it's a no-brainer for me.

Good luck
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.