So if I understand it correctly, you want to duplicate the template list, is that right?
You can Ctrl+drag it to the same level to copy it. This way you don’t need to engage in text manipulation and have no problems like “When I paste the children, the cursor ends up one level in, so subsequent pastes nests the node down a level. I want the pasted node to be at the top level where the paste was initiated”.
You can Ctrl+A twice to select an item. Repeating Ctrl+A will select a level upward.
I’m not sure what you mean by “unless it is first opened” in No. 2, by “opened” do you mean “expanded”?
If you use the Ctrl+A and copy/paste method, the collapsed children should be copied over as well, just in their collapsed states.
Lastly, there’s a customizable shortcut that can duplicate the current edited item and all its children, but that’s custom shortcut is a Dynalist Pro feature.
I hope that helps.