I think the order matters, but it also depends on whether the opponents are rated higher or lower than you. Maybe in some cases win 1st lose 2nd may be better.
I dont like the idea of using the end rating, it becomes a mess if your opponent times out in a lot of games, and his rating drops by 100's of points during your game.
I think that, when calculating the change in rating at the conclusion of a game, chess.com uses your rating at that moment (not the rating at the start of the game) right? So imagine if I'm playing two people and both games are nearing the end, and one game I'm probably going to lose, and the other I'm probably going to win. I think I'm better off resigning the lost game before winning the won game, right? In other words, it's better to lose before winning, than win before losing in terms of the total effect on your rating, right?