well... mobi files should work on a kindle since it is the native format. most drm'ed epub files are protected by adobe's adept drm scheme. to learn more, do a web search for inept cabbage. it's usually the first link.
as far as most of the apps for getting around drm, these are usually command-line apps because they are usually made by sigle-person teams working parttime on it, and the programs iterate very fast to keep up with changes in drm schemes and to fix bugs. these guys have very little time to build a gui.
also, most computers run windows, and so most gui programs will be windows-specific. a command-line app is much easier to port between windows/mac/linux/bsd if written properly.
i find the command-line tools to be rather simple, as i grew up using ms-dos. i would say that some exposure to a command-line environment will make using these tools much easier. however, the mac allows drag-and-drop between finder.app and terminal.app, making things much easier.
dear mods: i hope saying something that seems as random as inept cabbage does not break forum rules. by the way, how does the recent ruling by the librarian of congress affect discussions of drm-circumvention to promote interoperability, e.g., convert a sony store ebook to read on a kindle?