What kind of bandiwdth is required for hostin?
 

just wondering is 3mbit/768kbit too little?

Thats plenty, as a general rule only about 5-10k is required per player, but if they are all next to each other in the same zone and all fighting this could go up. Total bandwidth is not really hard to get enough of with a good cable or DSL, The thing you need to worry about is lag and reliability of delivery of packets. If you get a lot of packet loss or it takes several seconds for all packts to get to or from you your connection on a hosted server will be terible even if you have a total bandwidth of like 100 mb/s. And the only real way to make sure your server is fine with that type of stuff is to create one and get people on to test it.