Can I make Galeon to open certain file types without asking first whether to open or save?
Adding this feature means we'd have to implement pretty much a complete MIME type database editor, which already exists in Nautilus. Such duplication of effort would be pointless and also having such a feature in Galeon would be illogical. You'd be picking the application in one place (Nautilus) and Open/Save/Ask in another (Galeon) or picking the application for GNOME desktop in one place and another application only for Galeon.
The list of file types to open always should be maintained somewhere else so that all applications (Galeon, Epiphany, Nautilus, ...) can agree on what to do with remote files. And as Nautilus is currently the place to choose the application from it's the most logical place to choose what to do with remote files as well.