My choice would be the Canon 70-200mm f/2.8 non-IS since sports would be your main love, in decent lighting you'll do fine without IS for portraits (given your budget). I have more confidence in the build of Canon's gear than Tamron or Sigma and the AF is better (Which is really important for sports!). It will get you more keepers in your porfolio overall than IS will with the Tamron.
I would get the 7D your situation or if your really big on sports the 1D III, I would not consider the FF unless sports where a low priority or as a second body. The number one overiding feature in sports is speed so you either have to compromise to do anything else (A 7D is a very good compromise) or spend more money.
Hope you his helps,
John.
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