Restore iPhone does not restore all settings

I have just replaced my damaged iPhone 3Gs with an identical one. When I restore the backup from the original phone, not all settings are restored. All my apps, photos and music etc are there, but missing are:

1. Passwords for 'remembered' WiFi networks - effectively they're no longer remembered
2. Passwords for various mail accounts
3. Cellular data network settings

Is this normal? Is there anyway, in particular, to restore all the WiFi networks?

Thanks in advance,
R