I'm afraid that both of these features are not currently implemented in the Gantt. For the first one, I would recommend suggesting it on UserVoice so that it gains some traction and gets implemented. For the second, you may use the drop event of the component that you are dragging from (e.g. Draggable, or TreeView) accordingly, but you'll need to determine the correct position of the newly created task, because there is no official API for that.
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