I agree with the other replies in this thread, but thought I should say that Omnifocus can do most of what you want. However, it's the app that launched a thousand posts. There are more reviews, set-up guides, tweaks, et cetera about Omnifocus than you can imagine, which should tell you something. It's a decent program, but it is no more essential for gtd than a rhinestone-studded day planner. Be careful what you wish for- you might get it.