In regards to the "skip-shifting", this is in a manual tranny car.
My dad always used to do it and that of course brought on the comments from my Mom, "Oh Roger, stop doing that! You are ruining the car." Well he never paid much attention to the advise and now I do the same thing.
I ask because I usually do this in our Toyota Tacoma at stop lights, 1st, 2nd to the speed I want then 4th to level the speed off quickly.
As for the automatic transmission downshifting, I am mainly addressing a situation where you may be cruising at a steady speed (60 mph) and then may have the need to downshift for a little passing, its faster to already be in the gear than to wait for the auto-kickdown from the transmission.
I have always let the engine so some of the breaking on down grades and even when coming to a stop (good practice of Heel-and-Toe technique even to first gear) so I want to avoid any potential long term damage, hence my questions.