solution to the two-floor elevator problems:
there are two arrows on each elevator/other transportation, one on top one on bottom. use the top one to extend it upward and the bottom to extend it downward.
dont use the tubes, they are inefficient transportation as people get in the way of eachother. use skyhooks and firepoles instead, they are just plain better.
i got the 4th ending. basically you must return to the main mennu and replay the ending with a different alien until you get them all. then... im not gonna spoil it for you!