Ursula has a reputation for being full of creepy/nerdy/quiet people. I know people from there (some like it, some don't - this is probably more reflective of college life than ursula itself) who are nice and not freaks and so on. Ursula and Bruce, I think, get the most amount of HDs on average. The rooms are smaller than all of the other catered colleges too, but I don't know how important that is to you. I think it has a smaller amount of people than all the other colleges too, which could be why they're known as the quiet ones.
There's inter-college almost everything sport competitions.
You can be fed relatively inexpensively. On campus in the student union place there's a reasonably priced baked-goods shop. It's always much cheaper to cook for yourself, though, when you can get dried pasta for 99c.
Downloads do count as quota unless you download on the wireless internet. However, I think wireless is monitored, so if you download giant files at a time, you'll probably lose access or something. If you download from an ANU webpage though, it's free.