I don't like the layout of summary and article buffer, how to change it? Perhaps even a three pane display?
You can control the windows configuration by calling the function gnus-add-configuration. The syntax is a bit complicated but explained very well in the manual node "Window Layout". Some popular examples:
Instead 25% summary 75% article buffer 35% summary and 65% article (the 1.0 for article means "take the remaining space"):
(gnus-add-configuration '(article (vertical 1.0 (summary .35 point) (article 1.0))))
A three pane layout, Group buffer on the left, summary buffer top-right, article buffer bottom-right:
(gnus-add-configuration '(article (horizontal 1.0 (vertical 25 (group 1.0)) (vertical 1.0 (summary 0.25 point) (article 1.0))))) (gnus-add-configuration '(summary (horizontal 1.0 (vertical 25 (group 1.0)) (vertical 1.0 (summary 1.0 point)))))