Tyler - nobody can tell you what ISO to use at your event since we have no idea what the ambient light is at your arena. I'd suggest shooting in Manual exposure mode if you're comfortable doing so, open your 70-200 f/2.8 up to f/2.8, and use your histogram to guide your setting for ISO to keep your shutter speeds >1/640s or so.
You'll want your histogram to be biased towards the right (since there will be a LOT of whites in the image). You also should do a custom white balance off the dirty ice, and be prepared for the colors to shift from shot to shot due to the arena's lights cycling in their own color.
If you're more comfortable with a program mode, select Av with evaluative metering
Check out the 2nd episode of the podcast in my signature for a lot of information on shooting indoor sports. It includes details on most of this stuff.
As far as lenses go, I shoot from the sides of the rink, about even with the face-off circle, with a 70-200. If you shoot from the corner, or behind the goal line, a longer lens will come in handy for getting the up-ice rushes. I also have employed a ladder like the one below to get over the glass/screen. Avoiding shooting through the scratchy glass makes a HUGE difference in the quality of the images. The platform of the ladder also make a nice place to rest a monopod, if you use one.
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