You'll find it's not useful to ask which gate a particular flight will depart from. Aside from some general patterns (U.S.-bound flights tend to go from 3/4/21, Australia from the high 60s) to which there are still exceptions, everything else is a total grab bag.

You'll also find that the which-lounge question has been discussed ad nauseum, including on the FAQ thread at the top of the forum. Cathay Boy has helpfully given you the cliffs notes version, although YMMV -- the new-car small of the Wing J has worn off for me, so I just go to whichever lounge is closer to my gate.

While another poster on this thread may have greeted you with a certain un-Canadian lack of friendliness and charm, FT tends to work best -- most information conveyed with least amount of irritation on all sides -- if users turn to FAQ threads and search first. I would still recommend you do that, since you'll find much more information on all the issues raised in this tread than we'll get to here.