How much server datatraffic to except?

#1 Acually it depends on allot more than that. Is this a First person shooter? or a Realtime Strategy? RolePlaying? Then you can decide what you want to send back and forth. live ammo projectile spreed. And then you could even use more network data by sending stuff the server client usually dosent need. Specific to your game..
For something like Halo since it is a big network hog, It can use 128kbps if you have 8 players. Im guessing the normal ISP Wont allow you to run a permenant game server. Just my Oppinion.

#2 I'm not talking about a server at home, but a dedicated server. But I just meant an aproximate guess of it, not a perfect calculation. Just something to have as a guideline.

#3 I went to the tribes admin forums and asked the same question more or less, still havent got an answer. I was after someone who had run a 32 or 64 player server to tell me approx how much bandwidth had been consumed.

Of course the amount of resources consumed will vary according to the game you do.

Hope you have better luck than me.

#4 You should find out the bandwith requirements perperson, and then gauge the costs based on the numbers of people you expect.

not rocket science, but it does require some computation.

That, and me not knowing how torque deals with network stuff, you might just want to get a network bandwidth monitor, and gauge by hand. (have some friends test your server, and see how much bandwidth they take)