You'll need to install php, apache and possibly mysql if you want to use a database. There will be precompiled packages for your distro, or you can compile them all from source if you want a different configuration or just to learn how to do it. As well as php.net, check out http://www.onlamp.com/
- an O'Reilly site about linux/apache/ mysql/ php development.
As far as an editor, I think quanta does php, I just use vim.