We do a lot of games here, most are casual as are our players....
We are playing all the new Commander decks (5) in a multi-player game, but there are players who like the duel style of play. Just ask for a game and what you are looking to play and someone may be interested.
Since this is a message board, all games are on the honor system. But if you want to try out a deck against a certain deck, just let us know what deck you want to play against and we can build it.
What "prebuilt", you mean the ones that come in a deck already from WOTC? Which set(s)? I have a few custom, but they're pretty old (no power nine though), like circa 2000 or so if you want to play against some older cards
Well, I think you said you took a look at some of the threads. We just post the board state basically as we draw and play cards and whatnot. For me, my decks are in Apprentice or Excel so I keep track of them that way; you can either do the same or play your deck "in front" of you as it plays (and if you have room and can keep it out for a while, as these games aren't quick).