I would argue there is very little benefit to Right Click over ESC. It still requires 1 click from a user just depends which hand. I personally have my hand on the keyboard at all times with easy access to the ESC key and would prefer it over the right click function as I would like proper right-click options when I press that button on my mouse.
That being said if this could be an option you have to opt into I wouldn't complain.
Again deselecting items when command is finished should be a user preference option as I find it very unhelpful when I am trying to do multiple things to a selection of elements. Again, my hand is ready to hit the ESC key at all times.
Unless I am completely misunderstanding you, single selection is the default. When I want to select multiple elements I have to hold the Ctrl key to do so. How does it work for you?
None of the suggestions you put forth are particular time savers in my opinion and so should all be opt in options if at all.