"Half-wheeling" can mean riding with your front wheel up the the rear axle of the next rider in a pace line or peloton, .... it is considered to be a poor-taste expression of impatience with the pace, and it is ridiculously dangerous, because the slightest waver by either rider causes the riders and most of the people behind them to hit the deck.
"Salmoning" is riding upstream----that is indeed the defining characteristic of salmon. (Well, that and breeding in the same place they were born .... not so much a cycling thing (that I have heard.)
"Wheel sucking" as I understand it, is getting on someone's wheel for a tow and staying there, never taking a pull. It is bad in a competition setting, and inexcusable on the road in a casual setting. In competition, it is a valid tactic, if one that doesn't make friends. On the road it is rude and stupid ... at least have the decency to talk to the person you plan to follow. I have the habit of standing up randomly, particularly if my heart or my lungs say "Rest Now! Right Now!" and anyone on my wheel is going to hit me. Which neither of us would appreciate, i am sure.