You mean with an AI that does nothing? You can set its resource multiplier to zero. (The current PTE has an "Idle" AI where you don't need to do that).
All bindings default, see settings/keyboard/dev mode. Hover over a unit and press ctrl+c, then press ctrl+v to paste a copy of it. alt+f1 and alt+f2 put an avatar or avatar factory in your paste buffer, use ctrl+v to create one. You can get some extra UI by launching the game with --devmode I've also made a bunch of mods that expose (instead of devmode) or enhance the UI: - Bulk Create Units - Improved Player Control - Sandbox Unit Organizer / Sandbox Unit Toolbox
To expand on @wondible's post - when copy/pasting units, make sure your cursor is hovering over the item to copy. Just selecting/highlighting it does not work. And when pasting, place your cursor to the area you'd like it to be pasted. In Settings > Keyboard > Dev Mode you'll find several hotkeys, however they do not explain that you need to CTRL+V after selecting ALT+F1 to add the Uber Fabber (avatar.)
