Nice tips again! Ctrl+click is a very useful one. I should mention that when you do this, envelopes are also copied, so that can save even more time!
And also about items: When you grab the edge of an item, you can cut it by dragging the cursor. However, you'll notice that Reaper automatically adjusts the movement to fixed positions (depending on the tempo and time signature). But, if you press the Shift key, you can drag the edge to wherever you want.
Note: The above also works when you move points in envelopes or when moving things in general (notes and edges of notes in the piano roll for example, which is nice for humanization!).