So you can already toggle between the one panel view and two panel view by clicking the "<" arrow in the header of the thread view, (although it doesn't actually expand the width of the text, it just centers the view and hides the list of other threads.) Or do you mean making the list of posts fullscreen?

To your second point, making a standard posts-only reverse chrono would be pretty easy, I could just add a toggle to show/hide replies. If I was going do that I would add the option for both the main feed and profile feeds.

Currently I'm redesigning the front page to handle communities better so these are good questions..