How to have two view panes in one Panel, so that selecting a node title in View A displays the content for that node in View B? Do I HAVE to use AJAX?
There is sort of a hackish way to implement such behavior, described on this answer: https://stackoverflow.com/a/1596756/1421920

In short, the answer suggests two displays of the same view, one with the titles on the left with exposed filters (hidden by CSS) and the other one with the acutal content of the nodes. Add JS to the titles to fill the other view's exposed filter (also hidden by CSS) and submit. The relevant node loads on the second view with AJAX.