I want to be able to add plugins for an application I am developing and as it is a development tool I want other people to be able to write their own plugins.
So my questions are what are the real differences between a framework and a loadable bundle? Which are more suited to being a plugin(accessing of headers, ect) ? And if I use loadable bundles how do I load them at runtime and access their functionality during development?
The plugins should not have to rely on other plugins.
Have you taken a look at NSBundle? It has all the methods you'll need to load the executable code at runtime. You'll want to define some sort of plugin interface to which any plugin will conform.
As for the difference between bundles and frameworks... Both bundles and frameworks are file structures that contain various resources that your app can use. A framework is like a library -- it's something your program links against when you build it. A bundle, on the other hand, is essentially a folder structure containing compiled code that you load at runtime.