You can save a project in Encore with your favorite settings, then use “save as” for each new project.
Open dynamic links from Encore rather than using “send” from Premiere.
But this only works for repetitive projects. Your examples, first play/end action, aren’t really settings. A new project has nothing in it. Encore already sets the first thing you add as first play. Add your menu first, it will be first play. (One of the reasons I’m suggesting you not use “send” from PR.) End actions can’t be set until the asset is added.
You could make a feature request for Encore to have a setting to automatically add a default end action to all timelines/slideshows/playlists created.
Stan Jones