That's awesome!

Don't sweat it, just go right into the code. I find drawing it out on graph paper (or at the very least getting a full mental picture) of how it will all function helps smooth out the rough concept so coding it becomes a bit more smooth.

I'm pretty anxious to see how the arena will look. Do you have anything special planned to make it different or are you going to try a more purist approach to that of games like Street Fighter and Mortal Kombat?