1. The portal is required. The portal is a separate form UDI service. The portal also allow a secure connection from anywhere. Port forwarding won't do it.
2. See 1.
3. Echo is a one room device, but you can add as many as you want.
4. You have to assign a "spoken" name for each device, scene and/or program that you want Echo to control.
5. The portal will find your devices and scenes when first installed. After that, you need to manually add or delete devices and/or scenes. Programs have to be added manually, but there's a drop down menu for each of devices, scenes and programs.