Getting started writing an add-on for EE2; also cache-ing utility

Greetings all,

I’ve been using EE 2 for awhile and I’m ready to start writing an add-on. I’m comfortable with PHP but don’t know how to create an add-on (working with parameters through EE, error handling bubbling up to EE, coding and use conventions, etc). Can someone please direct me to some docs on how to write EE 2 add-ons?

Also, I’m wondering specifically if there is a file-based or MySQL-(EE database)-based server-side cache utility I can use in my add-on. I see that CodeIgniter has a caching driver (http://ellislab.com/codeigniter/user-guide/libraries/caching.html) but the documentation is pretty thin and it doesn’t look like it could use MySQL for the data store. Also I can’t tell how it handles concurrency. I wrote my own cache code which will work for concurrent read/writes but I’d rather use a robust, well-tested cache utility.

Thanks, -NorthK