The bandwidth setting puts a cap on your transmit speed. So you need to have an idea about what sort of connection you have, and what sort of connection the other end has. If in doubt, choose a lower setting. It works much better when you aren't pushing the network to its limits.
When entering IP address, the key puts the in. To dial quick dials, you pick up the handset, press # and then press the key for the quick dial you want.
If you want to make a test call, then call 81.144.139.34 at 256kbit/s.