Yeah, they did back during the public beta. Although they didn't say they were against an Objective Arena, they just weren't sure on how to record all the different elements of how people play objective games and convert that to a rank. Slayer is based on kills (your kills, your deaths, how you kill etc) but a player can get through a whole objective game without a single medal, single kill or any points but still be crucial to the team. A designated driver, for example, maybe take an unguarded path (no enemies to splatter) while his passenger scores a point for the flag. And you can't just use kills because one team's strategy may be to lure the enemy away from their base, allowing for someone to sneak in. If you keep killing them then they'll respawn closer to the base than you would like them. I do like the playlists. This seems to have worked out much better than just "ranked" and "social".
Most likely fake. A couple weeks back Shishka mentioned there is no plans for a Infection Playlist at start, but not out of the cards. And yes, Shishka did make the playlists for Reach's launch before he left.
It was a question asked on krunchtaculars youtube channel, with a guy that went to comic-con. He asked and I believe shishka denied it. Fingers crossed eh
Um the list is real believe it or not, a Bungie representitive announced this list at GameCom. About the Arena Doubles playlist, I'm not sure, perhaps they've trashed it for some reason or maybe it won't be available at first but will be added in later. I'm not a Bungie employee or anything, so I don't know the answers to all you guys's questions.