You've gotten some good opinions here. You have a nice 2.8 pro-zoom, unless you want something wider (the 17 - 55mm f 2.8 on a D200 or better would be nice) to get in more of the court/ action, & since you want more dof - why worry about something faster?"
Try ISO 1600 or even 3200 - (the newly announced Canon Mk III offers ISO to 6400 & 10 fps).
More memory. Shoot a lot. In action shooting their will be many "throw-aways" for each keeper.