For poses, File>Save as>Pose preset...., but the saved items will be in DAZ|Studio format and so won't appear in the Content palette when viewing a Poser content directory. You can access yhem either by saving them to a D|S content directory and viewing that in the Content palette or by using File>Merge (if it's something you're going to use often, bring it up in the Content palette then right-click and select mak custom action which will add it to the Scripts menu). You can also use the free Poser format exporter to save a Poser format pose file.

At the moment the only way to save things is as a scene. That means you can't save parenting information, so there's no way to mimic the Poser smart prop system (though I think you could do it with a handwritten script, the Snap parent command is a script itself).