You can specify podcast behavior for all newly added podcasts using the "Podcast Preferences" option in the "Star" tab. The configuration you set here will be applied to all newly added podcasts, and be used for any existing podcasts that have not overridden the default settings.
You can specify unique podcast behavior any given podcast by accessing the podcast's Preferences in the menu available in the upper right of the podcast episode list display. The configuration you set through this menu will only apply to the given podcast.
The following guide might help in understanding what each setting does.