I would ask you first if you have ever played fighting games on that large of a screen, or on a projector before?
I ask that because it is extremely overrated in my opinion. I have played on my projector a few times and find that the size of the image makes it hard for me to focus on the game. Maybe I am just distracted by the size of the thing and I would get used to it, but I think it just doesn't fit into my vision that well. Maybe if I was sitting further away from the image, but then what would be the point? Also, I don't like sitting across the room from the image when I am playing fighting games, I need some kind of directness.
Anyway, aside from my own prejudices against playing games on a projector, there are other concerns. like Ginsu says, any motion from people moving the joysticks and hammering the buttons is going to move the image. In addition to that, projectors really do not like being moved while they are in operation, and it is easy to make a bulb in one explode by giving it a shock. I don't know if higher end projectors have this problem, but in the past they were notorious for it.
AND, I don't know about your friends, but whenever my friends come over to play, it can get pretty intense. Wires running everywhere, three TV's running at once, fifteen people crammed into a tiny room. If you have a big screen setup for SF4 and have any number of fellow fighting gamers over you can bet that it will get rowdy pretty quick. It would be the worst thing ever for a drunk person to knock the SF unit over and break a $1000 projector.
So I do not recommend putting the projector and the controls in the same housing.
What you could do is create a short box that will house your SF4 board, power supply, and speakers. The projector would sit on top of this box. You can put 15 connectors on the back of the box like a supergun and then build indivicual control panels for each player, or build a large single control panel box that is rock solid and stable for serious SF play. OR you could buy adapters from the user "Laugh" on shoryuken.com and use playstation 2 joysticks for your controls.
As far as the subwoofer goes, I don't really know if you will want to put into into the box with the projector or in the control panel. Either case has it's disadvantage. The sub wil vibrate the projector, which is bad, or it will vibrate the players hands, which I know is annoying from experience. You could always put the sub and other speakers in a separate audio box, and that would solve the problem, but then you would have three separate boxes just to play the game. Don't know if you want to go with that convoluted of a setup. It wouldn't bother me, but I kow a lot of people like cleaner setups.
I'm also going to be making a SF4 setup based on the pc version, but I'm just going to be building something smaller. I am going to try to build a wooden cab that is inspired by the vewlix cabinet that the game runs on in arcades. It's not going to be anything fancy, just a sit down cabinet with a widescreen monitor. I'm going to use the exact same controls, control panel dimensions and height as the cab. I only need it to be functionally the same as the vewlix, not nearly as expensive or complex though.