wp idea stream custom.php
If you want to extend/customize some functionalities of the plugin, then i advise you to use the wp-idea-stream-custom.php file. Using it you will be sure WP Idea Stream will load your custom functions and if you deactivate the plugin, then it won't break anything as this file will no more be loaded.
That's the great advantage of it against putting functions into the functions.php file of your theme.
This technique reminds you something? Actually it's the same one as the BuddyPress way of adding custom functions using the bp-custom.php file ;)
To let WP Idea Stream load your wp-idea-stream-custom.php, you simply need to place it at the root of the WordPress plugins directory /wp-content/plugins/
From this specific file, i think you'll have few limits in transforming WP Idea Stream to what you always dreamed of! There are more than 230 filters and 70 actions you can hook to from this file.
Here's an example of a wp-idea-stream-custom.php file containing some custom functions. I think you'll be interested by how you can add custom fields.
When using WP Idea Stream on a multisite config, it can be interesting to include some custom features that can be different for each or some blogs. Since version 2.2.0 of the plugin, it's of course always possible to add a global wp-idea-stream-custom.php file that will be loaded for each blog, but it's also possible to add a custom file for the current blog by creating a file named: wp-idea-stream-custom-[blog_id].php where you can replace [blog_id] with the blog id of the blog you wish to include very specific features to.
For example: as shown on the above image, you can add a wp-idea-stream-custom-2.php file which will only be loaded when the current blog of the network being browsed is the one having the ID == 2.