PHP
I've done a bit of this now. PHP is very easy to throw something quickly together. I wouldn't use it for a large system though - it's the BASIC of web programming. (For a large complex system I'd go for Django.)
An example is the registration form I knocked out for the Installfest at short notice. It's not code I'm very proud of, but it might be useful to you.
Widgets
For quick and dirty table editing I've used phpMyEdit http://phpmyedit.org. Good for administration screens.
Questions
Q. What's the best way to load a file?
A. Well the simplest is just to use the include statement, but because that will execute any PHP code in the file it is better to use file_get_contents(filename);
Documentation
There's a tutorial at http://nz.php.net/tut.php, and the manual http://www.php.net/docs.php.
Theres a bunch of PHP community sites...
But http://www.php.net is the main one.
Tools
There are some IDEs/debuggers...
